Deprecate all Injecting Aspect Code (backport #4415)

[mergify]

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.

---

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

[mergify]

Cherry-pick of d292a5e has failed:

On branch mergify/bp/6.x/pr-4415
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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

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