fix: Stage controller objects that batch repeated relative/absolute calls and emit moveFinished when done

[tlambert03]

This is an attempt to fix #410 ... it's still a WIP, but it introduces a _ValueBatcher object, a generic object that knows how to get/set and add values, and check device busy state. It manages repeated calls to add_relative and/or set_absolute, and, maintains an internal awareness of whether we're "done" or not.

That all sounds rather abstract, and it is, but the goal is to have one object that we can share (across, say, the stage controller widget, and the stage explorer widget #400 ... that coordinates all of the attempts to control and move the stage, and, importantly, lets them all know when the job is done so they can, for example, snap an image.

The value batcher itself doesn't manage an event loop, and could be moved into pymmcore-plus. It is wrapped here with a small QObject that does have the timer, polls the controller, and emits the signal when needed.

Here is a concrete example of what it enables (there's still one little glitch that can be seen in the movie... and I'm not yet sure if that's a bug in this code, or the demo stage device adapter). Note that you can press the relative move button twice (before it's done) and it still makes a 2x movement.

Untitled.mov

[tlambert03]

hey @fdrgsp, would you mind banging on this for a little bit and trying to break it?

[tlambert03]

this now uses pymmcore-plus v0.14 with pymmcore-plus/pymmcore-plus#462

[codecov]

Codecov Report

Attention: Patch coverage is 96.96970% with 2 lines in your changes missing coverage. Please review.

Project coverage is 90.47%. Comparing base (1175bba) to head (14132c3).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...rc/pymmcore_widgets/control/_q_stage_controller.py	95.55%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #423      +/-   ##
==========================================
- Coverage   90.52%   90.47%   -0.05%     
==========================================
  Files          89       90       +1     
  Lines        9791     9816      +25     
==========================================
+ Hits         8863     8881      +18     
- Misses        928      935       +7     

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[tlambert03]

this is looking pretty good. here's a real scope (it's a bit extra laggy, because this was also over remove desktop):

Untitled.mov