DM-47085: Refactor getTemplate run/runQuantum/getOverlappingExposures

[parejkoj]

Placeholder, including the commits from DM-47084 (will rebase onto main once that merges) - rebased to main, only the one final RFC commit.

[arunkannawadi]

Passing various inputs as keyword-only arguments is certainly much cleaner. Aside from the minor inline reviews, two larger changes requests are:

1. Since GetDcrTemplateTask inherits from GetTemplateTask, the API changes to getOverlappingExposures should be reflected in the former as well.
2. Although DM-CCB has approved the change, a user of this public method might get annoyed by the changing API without a deprecation warning. I'd suggest renaming the method to getOverlappingCoaddExposures or something, and define getOverlappingExposures (with deprecated decorator) as something that rips out the quantities from inputs and calls getOverlappingCoaddExposures.

[arunkannawadi]

Suggested change

	def runQuantum(self, butlerQC, inputRefs, outputRefs):
	def runQuantum(self, butlerQC, inputRefs, outputRefs):
	# Docstring inherited.

[parejkoj]

Do we really need to put this everywhere there isn't a docstring? I don't see this mentioned in the dev guide, and always figured that if there isn't a docstring it was implied.

[arunkannawadi]

Well, it was more of a suggestion here. The lack of docstring jumps out sometimes, and seeing that comment reassures that it's not needed. This could be just me.

[parejkoj]

The problem with modifying GetDcrTemplateTask is that it's even less well-tested than the base class (which doesn't have any unittests, only ci_ap). I'll can do my best to update it, but I was leaving it intentionally broken so that if someone tries to use it it will be clear it needs work.

[parejkoj]

Similarly, I'll change names and add a deprecated version, but I can't guarantee that it will work because it won't be tested.

[parejkoj]

Following up: I'm not going to touch GetDcrTemplateTask: it will need a new runQuantum, too, and it is not used anywhere in our current code, so there's no way to even theoretically test it. I'll file a separate ticket to bring it up to date, and let the DCR folks sort out whether they want to do that, or remove it.

[parejkoj]

I've filed https://rubinobs.atlassian.net/browse/DM-49079 about the Dcr template code. I believe I've incorporated all the rest of your suggestions.