WIP: phaseplot widget, export layers to yt ds

[chrishavlin]

This PR adds:

• a convenience function for exporting layers loaded in napari to a uniform grid yt ds
• a new phaseplot widget

may split those to separate prs...

[codecov]

Codecov Report

Attention: Patch coverage is 4.23729% with 113 lines in your changes missing coverage. Please review.

Project coverage is 95.74%. Comparing base (eb16ab0) to head (2d6cd32).
Report is 16 commits behind head on main.

Files with missing lines	Patch %	Lines
src/yt_napari/_widget_2d_plots.py	0.00%	80 Missing ⚠️
src/yt_napari/viewer.py	9.37%	29 Missing ⚠️
src/yt_napari/_gui_utilities.py	33.33%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #152      +/-   ##
==========================================
- Coverage   99.60%   95.74%   -3.86%     
==========================================
  Files          37       38       +1     
  Lines        2799     2917     +118     
==========================================
+ Hits         2788     2793       +5     
- Misses         11      124     +113     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[chrishavlin]

Still needs a bunch of UI design and fixes:

• labels (those drop downs are the PhasePlot x, y, z and weight field arguments
• add options for the rest of the PhasePlot arguments
• add some options for plot callbacks (log switches, colormap, etc)
• the matplotlib figure does not rescale well with the window

but there's a figure!