The builtin passes and apply_pass use qml.transform(pass_name="name")

[lillian542]

Context:
If you use apply_pass with program capture enabled, everything runs but it does not apply the pass. The same problem is true for any builtin pass that is accessed via from catalyst.passes import pass_name. This has created some situations that are difficult to debug.

Description of the Change:
We switch the apply_pass function to use the more general qml.transform(pass_name="name-of-pass") UI instead of PassPipelineWrapper, which isn't compatible with program capture. We also update the builtin passes to use the new more general UI.

Note that there are still two functions in the pass_api, pipeline and apply_pass_plugin, that do return a PassPipelineWrapper, so it is still currently possible to encounter one in specific cases.

Benefits:
Less confusing behaviour when switching to program capture.

Downsides

• The PassPipelineWrapper raised a clear error message if passed a non-Qnode function, and these errors are no longer raised when we switch to qml.transform.
• The pipeline and apply_pass_plugin will still return PassPipelineWrapper, which creates an issue if these are used alongside (specifically if they are used before) builtin passes or qml.transform(pass_name...)

[sc-112140][sc-104261]

[paul0403]

@dime10 Now that we have @qml.transform(pass_name="..."), which works with both with and without capture, @albi3ro suggested that we can deprecate catalyst legacy frontend's own @apply_pass, which currently silently does nothing when capture is enabled (instead of explicitly telling the user the pass will not be applied).

Any objections?

[dime10]

@dime10 Now that we have @qml.transform(pass_name="..."), which works with both with and without capture, @albi3ro suggested that we can deprecate catalyst legacy frontend's own @apply_pass, which currently silently does nothing when capture is enabled (instead of explicitly telling the user the pass will not be applied).

Any objections?

Sure, just check with @isaacdevlugt

[albi3ro]

We can also just update the implementation to use transform(pass_name=pass_name) for the time being.

[github-actions]

Hello. You may have forgotten to update the changelog!
Please edit doc/releases/changelog-dev.md on your branch with:

• A one-to-two sentence description of the change. You may include a small working example for new features.
• A link back to this PR.
• Your name (or GitHub username) in the contributors section.

[isaacdevlugt]

@dime10 Now that we have @qml.transform(pass_name="..."), which works with both with and without capture, @albi3ro suggested that we can deprecate catalyst legacy frontend's own @apply_pass, which currently silently does nothing when capture is enabled (instead of explicitly telling the user the pass will not be applied).
Any objections?

Sure, just check with @isaacdevlugt

@dime10 @albi3ro no issues from my side :). We have something better now!

[paul0403]

@lillian542 feel free to delete all the jaxpr lit tests (and I guess the jaxpr printer itself)! Now that we don't go through catalyst legacy frontend's own mechanism, there's no need to check these anymore. The important part of the lit tests is the generated MLIR, as long as those are correct, we're fine.

[paul0403]

Note that "frontend tests" CI fails but "frontend tests: kokkos" CI succeeds because frontend lit tests are only run in the "frontend tests" job, if you were wondering.

[andrijapau]

Closing in favour of #2525 which contains these changes and some other improvements.