Deprecate more Aspect parts (backport #4420)

[mergify]

Deprecate the remaining parts of Aspects that were missed in earlier commits. After this, the only non-deprecated part of the aop library are the Select utilities.

Release Notes

Deprecate everything in aop package except Select library.

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This is an automatic backport of pull request #4420 done by Mergify.

[mergify]

Cherry-pick of e213eda has failed:

On branch mergify/bp/6.x/pr-4420
Your branch is up to date with 'origin/6.x'.

You are currently cherry-picking commit e213edaed.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   core/src/main/scala/chisel3/aop/Aspect.scala
	modified:   src/main/scala/chisel3/aop/AspectLibrary.scala
	modified:   src/main/scala/chisel3/aop/inspecting/InspectingAspect.scala
	modified:   src/main/scala/chisel3/stage/phases/AspectPhase.scala
	modified:   src/main/scala/chisel3/stage/phases/MaybeAspectPhase.scala

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   build.sbt

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