Misc - Post #1937 TODOs for FB

[mscuthbert]

PR #1937 was a complex enough PR that the misc changes I saw there I wanted to record for later. Just got through features and figuredBass/[a-p].*.py

• in figuredBass/checker.py these lines seem like they want to use .template().flatten() instead?

    newParts: list[stream.Stream] = [
        allParts[i].flatten().getElementsNotOfClass('GeneralNote').stream()
        for i in range(len(allParts))
    ]

• rename hiddenFifth to hiddenFifths and same with hiddenOctave, if the logic is the same as parallelFifths/Octaves

• if music21GeneralNote.isNote -> use isinstance -- now fast enough. isNote is on the chopping block.

• figuredBass/notation.py -- figure out why "origNumbers" and "numbers" can have strings not just ints.

• figuredBass/possibility.py -- couldBeItalianA6Resolution -- remove casts on third, fifth -- they might be None! test for that instead.

• if debug is True, etc.

• Hash pitch outcomes by nameWithOctave -- old hashablePitch is gone. -- no pitches ARE hashable! so the caches work! (Test at least one)

• Use the same cache parallelFifthsTable in possibility.py and checker.py -- but should we be using VLQs anyhow?

• Update this doc in possibilities to note that the bass is often not included

# A possibility is a tuple of pitches, one per part, ordered from the highest
# part to the lowest part (the last element is the bass). 

• partPairs -- zip to zip strict=True
• realizerScale: scaleValue -> scaleTonic
• realizerScale: getPitchNames -- notationString: str = '' -- find similar places (getSamplePitches and getPitches all similar)
• realizerScale: t.cast(int, maxPitch.octave) -- no -- just maxPitch.implicitOctave
• segment.Segment - and perhaps others - make a ProtoM21Object -- segment --notationString: str = ''? (but change later in init... -- what happens if notationString is not None and listOfPitches is not None -- listOfPitches vanishes?? --
• resolveDominantSeventhSegment -- document that major scale will always have tonic, ^4, ^6, etc. same for dim seventh segment.
• segment -- remove bare inserts added in Add typing to figuredBass #1940
• realizer -- addLyricsToBassNote -- notationString = '' -- addElement would change bassObject.editorial.notationString slightly, but not in a way I think it would matter? Need to check.
• realizer -- addElement -- switch to isinstance, which should get rid of the checking. (is Harmony the type we want anyhow? Maybe...but if NoChord() is a Harmony object then we're in trouble... so maybe the union class is still best.)
• realizer.realize -- switch on .classes should use isinstance.
• realizer _trimAllMovements -- should probably set movementsAB: dict[...] = {} -- then no problem. Creating one additional empty dict is almost a no-op. THen no need to do the movementsABFinal recasting.
• Realization -- no point in typing **fbLineOutputs as t.Any. -> None is good enough to get typeChecking, but the class should have typed attributes.