Ability to pass custom passes from nvq++

[1tnguyen]

Description

Ability to pass custom pass plugins (as .so files) from nvq++ to cudaq-opt and adding its passes to the pipeline.

Resolved #969

[github-actions]

CUDA Quantum Docs Bot: A preview of the documentation can be found here.

[github-actions]

CUDA Quantum Docs Bot: A preview of the documentation can be found here.

[amccaskey]

I know this has been merged, but one thing I'll add here is that we need to figure out how an external user can build custom pass plugins apart from CUDA Quantum (real plugins, without requiring a fork of the main repo). I think this is probably as straightforward as ensuring that our MLIR headers are installed (which they are not now).

[1tnguyen]

I know this has been merged, but one thing I'll add here is that we need to figure out how an external user can build custom pass plugins apart from CUDA Quantum (real plugins, without requiring a fork of the main repo). I think this is probably as straightforward as ensuring that our MLIR headers are installed (which they are not now).

Good point! I've posted #1037 to track this.