Add Data.findFirstTypeMismatch for better type checking (#3201)

This utility provides a way to check different versions of type
equivalence in Chisel internals and generates error messages for when
mismatches are found. Specifically, it handles structural vs. nominal
typing as well as strict vs. non-strict width checking.

(cherry picked from commit 6e7c4764)

# Conflicts:
#	core/src/main/scala/chisel3/Aggregate.scala
#	core/src/main/scala/chisel3/Clock.scala
#	core/src/main/scala/chisel3/experimental/Analog.scala