[Utils] Add return_unmatched argument to match_modules_set

[kylesayrs]

Purpose

• Add support for returning any unmatched sets when using match_modules_set
  • This is useful for more verbose/specific erroring in the case of checking for fused modules

Changes

• Fix typo FusedMappping -> FusedMapping`
• Fix typo in match_modules_set docstring
• Add return_unmatched argument to match_modules_set
• More verbose error when double matching in match_modules_set

Returned values from generators can be accessed in the following way:

matched_modules = []
unmatched_module = None
try:
  while True:
      matched_modules.append(next(match_modules_set(model, targets, return_unmatched=True)))
except StopIteration as exception:
  unmatched_module = exception.value

Testing

• Added test_incomplete_set_return