Support Optionality of implicit clock and reset

[jackkoenig]

This is in preparation for the new LTL operators defaulting to using the current in scope clock (needs Option[Clock]) and making it easy to disable clock for a region of assertions.

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you add appropriate documentation in docs/src?
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• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• Feature (or new API)

Desired Merge Strategy

• Squash

Release Notes

• withClock, withReset, and withClockAndReset now have forms that take Option[Clock] and Option[Reset]
• Module.clockOption and Module.resetOption return Option[Clock] and Option[Reset]

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels? (Select the most appropriate one based on the "Type of Improvement")
• Did you mark the proper milestone (Bug fix: 3.5.x, 3.6.x, or 5.x depending on impact, API modification or big change: 6.0)?
• Did you review?
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• Did you do one of the following when ready to merge:
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[seldridge]

LGTM

This is generally useful to be able to unset the clock/reset ignoring the LTL use case. 👍