This method was added to fix a performance regression introduced by Qiskit#13921. This check should be quicker than the multiple calls to `isinstance`.

In Qiskit#13921 a check was added to circuit_to_instruction() for determining
if the circuit has a control flow op. This check was adding significant
overhead to the function, nightly asv benchmarks are showing up to a ~9x
slowdown. Qiskit#13921 attempted to fix this regression but did so by adding a
new API which isn't applicable at this point for 2.0. That PR could/should
still be used in 2.1. In the meantime this commit seeks to solve the
performance regression by adjusting how the check is performed to
mitigate the runtime regression for 2.0.

In #13921 a check was added to circuit_to_instruction() for determining
if the circuit has a control flow op. This check was adding significant
overhead to the function, nightly asv benchmarks are showing up to a ~9x
slowdown. #13921 attempted to fix this regression but did so by adding a
new API which isn't applicable at this point for 2.0. That PR could/should
still be used in 2.1. In the meantime this commit seeks to solve the
performance regression by adjusting how the check is performed to
mitigate the runtime regression for 2.0.

* Add: Add method has_control_flow_op(), to `QuantumCircuit`

This method was added to fix a performance regression introduced by #13921. This check should be quicker than the multiple calls to `isinstance`.

* Lint: Fix formatting

* Lint: Removed unused import and f-string

* Docs: Add release note
- Add `has_control_flow_op` to autogenerate docs.

* Fix: Addressing review comments

Co-authored-by: Matthew Treinish <mtreinish@kortar.org>

* Docs: Fix formatting issue in `QuantumCircuit` docstring.

* Lint: Fix formatting bug in `QuantumCircuit`.

* Test: Add testcases
- One test case with a regular control flow operation and another with a custom one.

* Test: Remove unsupported test and extend original test.
- Implement a combinatorics based test for control flow operations.

* Fix: Import order in `test_circuit_operations`

* Update test/python/circuit/test_circuit_operations.py

---------

Co-authored-by: Matthew Treinish <mtreinish@kortar.org>

* Add: Add method has_control_flow_op(), to `QuantumCircuit`

This method was added to fix a performance regression introduced by Qiskit#13921. This check should be quicker than the multiple calls to `isinstance`.

* Lint: Fix formatting

* Lint: Removed unused import and f-string

* Docs: Add release note
- Add `has_control_flow_op` to autogenerate docs.

* Fix: Addressing review comments

Co-authored-by: Matthew Treinish <mtreinish@kortar.org>

* Docs: Fix formatting issue in `QuantumCircuit` docstring.

* Lint: Fix formatting bug in `QuantumCircuit`.

* Test: Add testcases
- One test case with a regular control flow operation and another with a custom one.

* Test: Remove unsupported test and extend original test.
- Implement a combinatorics based test for control flow operations.

* Fix: Import order in `test_circuit_operations`

* Update test/python/circuit/test_circuit_operations.py

---------

Co-authored-by: Matthew Treinish <mtreinish@kortar.org>