…ithin net_processing.{h,cpp}

8b3136b refactor: replace CNode pointers by references within net_processing.{h,cpp} (Sebastian Falbesoner)

Pull request description:

  This PR is inspired by a [recent code review comment](bitcoin#19010 (comment)) on a PR that introduced new functions to the net_processing module. The point of the discussion was basically that whenever we pass something not by value (in the concrete example it was about `CNode*` and `CConnman*`) we should either use
  * a pointer (```CType*```) with null pointer check or
  * a reference (```CType&```)

  To keep things simple, this PR for a first approach
  * only tackles `CNode*` pointers
  * only within the net_processing module, i.e. no changes that would need adaption in other modules
  * keeps the names of the variables as they are

  I'm aware that PRs like this are kind of a PITA to review, but I think the code quality would increase if we get rid of pointers without nullptr check -- bloating up the code by adding all the missing checks would be the worse alternative, in my opinion.

  Possible follow-up PRs, in case this is received well:
  * replace CNode pointers by references for net module
  * replace CConnman pointers by references for net_processing module
  * ...

ACKs for top commit:
  MarcoFalke:
    ACK 8b3136b 🔻
  practicalswift:
    ACK 8b3136b

Tree-SHA512: 15b6a569ecdcb39341002b9f4e09b38ed4df077e3a3a50dfb1b72d98bdc9f9769c7c504f106456aa7748af8591af7bb836b72d46086df715ab116e4ac3224b3b

…tx_verify.{h,cpp}

b00266f refactor: replace pointers by references within tx_verify.{h,cpp} (Sebastian Falbesoner)

Pull request description:

  This PR gets rid of another unnecessary use of raw pointers, similar to PR bitcoin#19053 (see also issue bitcoin#19062 where useful commands for finding potential candidates are listed) but in the tx verification module.

  For the functions `CalculateSequenceLocks()` and `SequenceLocks()`, the  `prevHeights` vector parameter type is changed to be passed as a reference. Note that there were no checks for null pointers -- if one would pass `nullptr` to one of the functions, the following line would immediately lead to a crash:
  https://github.com/bitcoin/bitcoin/blob/dcacea096e029a02a937bf96d002ca7e94c48c15/src/consensus/tx_verify.cpp#L32

ACKs for top commit:
  Empact:
    Code Review ACK bitcoin@b00266f

Tree-SHA512: 0eb71591467905434082029128bdca4df94988c372af40dca325654f6c002c72a00c73776cb5e72d6de2b2f218649211a5dbf19300a2e01f1841d6034e0f01e0

…tx_verify.{h,cpp}

b00266f refactor: replace pointers by references within tx_verify.{h,cpp} (Sebastian Falbesoner)

Pull request description:

  This PR gets rid of another unnecessary use of raw pointers, similar to PR bitcoin#19053 (see also issue bitcoin#19062 where useful commands for finding potential candidates are listed) but in the tx verification module.

  For the functions `CalculateSequenceLocks()` and `SequenceLocks()`, the  `prevHeights` vector parameter type is changed to be passed as a reference. Note that there were no checks for null pointers -- if one would pass `nullptr` to one of the functions, the following line would immediately lead to a crash:
  https://github.com/bitcoin/bitcoin/blob/dcacea096e029a02a937bf96d002ca7e94c48c15/src/consensus/tx_verify.cpp#L32

ACKs for top commit:
  Empact:
    Code Review ACK bitcoin@b00266f

Tree-SHA512: 0eb71591467905434082029128bdca4df94988c372af40dca325654f6c002c72a00c73776cb5e72d6de2b2f218649211a5dbf19300a2e01f1841d6034e0f01e0

…t_processing.cpp

0c8461a refactor: replace CConnman pointers by references in net_processing.cpp (Sebastian Falbesoner)

Pull request description:

  This is a follow-up to the recently merged PR bitcoin/bitcoin#19053, replacing ~~two more types of~~ one more type of pointer (CConnman) by references to increase the code quality -- pointers should either check for `nullptr` or be replaced by references, and the latter strategy seems to be more reasonable.

  Again, to keep the review burden managable, the changes are kept simple,
  * only tackling `CConnman*` ~~and `BanMan*`~~ pointers
  * only within the net_processing module, i.e. no changes that would need adaption in other modules
  * keeping the names of the variables as they are

ACKs for top commit:
  jnewbery:
    utACK 0c8461a
  MarcoFalke:
    ACK 0c8461a 🕧

Tree-SHA512: 79dc05144bcfb5e0bbc62180285aadcc6199f044fa3016c0f54f7b7f45037415260970037bd63b18fafefb8aef448549dae14b780bafb540fa2373f493a17f71

…s in net_processing.cpp

0c8461a refactor: replace CConnman pointers by references in net_processing.cpp (Sebastian Falbesoner)

Pull request description:

  This is a follow-up to the recently merged PR bitcoin#19053, replacing ~~two more types of~~ one more type of pointer (CConnman) by references to increase the code quality -- pointers should either check for `nullptr` or be replaced by references, and the latter strategy seems to be more reasonable.

  Again, to keep the review burden managable, the changes are kept simple,
  * only tackling `CConnman*` ~~and `BanMan*`~~ pointers
  * only within the net_processing module, i.e. no changes that would need adaption in other modules
  * keeping the names of the variables as they are

ACKs for top commit:
  jnewbery:
    utACK 0c8461a
  MarcoFalke:
    ACK 0c8461a 🕧

Tree-SHA512: 79dc05144bcfb5e0bbc62180285aadcc6199f044fa3016c0f54f7b7f45037415260970037bd63b18fafefb8aef448549dae14b780bafb540fa2373f493a17f71

…{h,cpp}

Summary:
```
This PR is inspired by a recent code review comment on a PR that
introduced new functions to the net_processing module. The point of the
discussion was basically that whenever we pass something not by value
(in the concrete example it was about CNode* and CConnman*) we should
either use

    a pointer (CType*) with null pointer check or
    a reference (CType&)

To keep things simple, this PR for a first approach

    only tackles CNode* pointers
    only within the net_processing module, i.e. no changes that would
need adaption in other modules
    keeps the names of the variables as they are

I'm aware that PRs like this are kind of a PITA to review, but I think
the code quality would increase if we get rid of pointers without
nullptr check -- bloating up the code by adding all the missing checks
would be the worse alternative, in my opinion.

Possible follow-up PRs, in case this is received well:

    replace CNode pointers by references for net module
    replace CConnman pointers by references for net_processing module
    ...
```

Backport of core [[bitcoin/bitcoin#19053 | PR19053]].

Depends on D8469.

Test Plan:
  ninja all check-all

Reviewers: #bitcoin_abc, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Subscribers: jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D8470