Deprecate all Injecting Aspect Code (backport #4415)

[mergify[bot]]

Deprecate injecting aspect code as of Chisel 6.6.0. These were planned to be deprecated some time ago (see ROADMAP.md). However, these had a long user in @sequencer. He is now off of these and there is nothing blocking their removal.

I will follow this with a commit to remove these from main for Chisel 7.

For similar, verification-focused functionality can be selectively added to the circuit, use layers.

Release Notes

Deprecate injecting aspects as of Chisel 6.6.0 and plan for removal in Chisel 7.

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This is an automatic backport of pull request #4415 done by Mergify.

[mergify[bot]]

Cherry-pick of d292a5eef1e9ebc2428b80c94ed603451277dd2d has failed:

On branch mergify/bp/6.x/pr-4415
Your branch is up to date with 'origin/6.x'.

You are currently cherry-picking commit d292a5eef.
  (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/ModuleAspect.scala
    modified:   src/main/scala/chisel3/aop/injecting/InjectStatement.scala
    modified:   src/main/scala/chisel3/aop/injecting/InjectingAspect.scala
    modified:   src/main/scala/chisel3/aop/injecting/InjectingPhase.scala
    modified:   src/main/scala/chisel3/stage/phases/MaybeInjectingPhase.scala

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

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally