This meta-issue tracks the actions required to have full wallet load/create/unload at runtime.

• Add locking to the global vpwallets to ensure no concurrency races when adding to the vector. This is sufficient thread safety for loadwallet and createwallet, but not unloadwallet (Add wallets management functions #13017 and Make vpwallets usage thread safe #13028).
• Add loadwallet RPC. Initially, this won't update the available wallets in the GUI ([wallet] loadwallet RPC - load wallet at runtime #10740)
• Hook up the loadwallet RPC to CClientUIInterface::LoadWallet() so newly loaded wallets are available in the GUI (ui: Support wallets loaded dynamically #13097)
• Add createwallet RPC. Initially, this won't update the available wallets in the GUI ([wallet] createwallet RPC - create new wallet at runtime #13058)
• Update vpwallets to be shared pointers (or similar) so that wallets can be freed safely (Use shared pointer to retain wallet instance #13063).
• Add unloadwallet RPC. Initially, this won't update the available wallets in the GUI (Add unloadwallet RPC #13111)
• Hook up the unloadwallet RPC to a new CClientUIInterface::UnloadWallet() function so unloaded wallets are removed from the GUI (Add unloadwallet RPC #13111)
• Add an "open wallet" command in bitcoin-qt (gui: Add Open Wallet menu #15153 and gui: Add Open External Wallet action #15204)
• Add a "close wallet" command in bitcoin-qt (gui: Add Close Wallet action #15195)
• Add a "create wallet" command in bitcoin-qt (gui: Create wallet menu option #15450)