[WIP] fix: fix lag in live mode after mda acquisition

[fdrgsp]

I've noticed that after opening napari-micromanager the live mode works well without any lag. However, after running a MDA acquisition, the live mode starts to lag. See video below to see this behavior.

As a proposed solution, I modified the CoreViewerLink class and use the same QTimer pattern that we use in the pymmcore-widgets ImagePreview widget (https://github.com/pymmcore-plus/pymmcore-widgets/blob/d5d38c9cc24bc2ac99b5921ac2593a4037d258fb/src/pymmcore_widgets/_image_widget.py#L18).

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CURRENT

current.mp4

FIX

fix.mp4

[tlambert03]

I'm curious if you determined that using an independent QTimer instead of self.startTimer was sufficient to resolve the slow down? I ask because this is a bit surprising to me. Before accepting this change, I'd prefer to know why it matters. Looking into the Qt docs for hints if need be. If true, it might have to do with threading or something... but lets figure out why we're doing it

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (41a9943) 78.92% compared to head (267fa38) 78.93%.

Files	Patch %	Lines
src/napari_micromanager/_core_link.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #309   +/-   ##
=======================================
  Coverage   78.92%   78.93%           
=======================================
  Files          15       15           
  Lines         688      693    +5     
=======================================
+ Hits          543      547    +4     
- Misses        145      146    +1     

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[tlambert03]

I think that ultimately, the problem here is the getExposure with a Hamamatsu camera is returning an artificially high exposure time as of December 14th 2023. See micro-manager/mmCoreAndDevices#442

So I think this can be closed.