Merge for v7.3.3

[raphaelquast]

Another round of bug-fixes for v7.3.

🌳 New

• MapsGrid objects now have dedicated .show() and .snapshot() methods

🔨 Fixes

• ❗ fix restoring visible layer in interactive backends after using m.savefig()
• ❗ fix issues with InsetMaps in ipympl backend
• fix re-drawing spines with m.set_frame() if corners are not rounded
• fix colorbar should use figure directly instead of relying on plt.gcf
• fix re-fetching backgrounds if colorbars change axes sizes
• fix parsing "maxsize" argument for raster-shape in companion-widget
• fix treatment of weighted colorbar histograms with (out_of_range_vals="masked")

[codecov[bot]]

Codecov Report

Attention: 10 lines in your changes are missing coverage. Please review.

Comparison is base (d2f3e79) 75.37% compared to head (ab2452d) 75.49%. Report is 2 commits behind head on master.

Files	Patch %	Lines
eomaps/eomaps.py	22.22%	7 Missing :warning:
eomaps/mapsgrid.py	66.66%	2 Missing :warning:
eomaps/colorbar.py	83.33%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #217 +/- ## ========================================== + Coverage 75.37% 75.49% +0.12% ========================================== Files 24 24 Lines 11115 11117 +2 ========================================== + Hits 8378 8393 +15 + Misses 2737 2724 -13 ```

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