Don't emit nodes when calling .asBool on a Bool (backport #3637) (#3638)

* Don't emit nodes when calling .asBool on a Bool

(cherry picked from commit d5e65a33

)

# Conflicts:
#	core/src/main/scala/chisel3/Bits.scala
#	src/test/scala/chiselTests/LTLSpec.scala
#	src/test/scala/chiselTests/VerificationSpec.scala

* Resolve backport conflicts

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Co-authored-by: Jack Koenig <koenig@sifive.com>