[WIP] Fix issue #6185

[javabster]

Summary

fixes #6185, depends on #6883

Replaces valid_layers with a _get_gate_instance function that iterates over all gates in standard library

Details and comments

To do:

• twolocal should throw error for multi-controlled gates
• should the rotation layer blocks only support single qubit gates? The two_local docstring says The rotation layers are single qubit gates applied on all qubits but even in main branch you can set rotation_blocks="cx" and it will work

[Cryoris]

This is superseded by #12009 -- thanks for the effort nevertheless! 🙂