[ENH] Color styled widget icons

[ales-erjavec]

Issue

Fixes: gh-270

Changes

Color widget icons based on current palette where appropriate.

By default when running in dark mode the colors are inverted to fit the background to foreground grayscale range.

Note that 'Color' is quite badly drawn.

But also add support for explicitly using palette styled widget icons like in biolab/orange3#6444

[PrimozGodec]

After checkout, these branch icons are oversized (see screenshot below). My setup is a laptop with a retina screen and an external "normal" screen plugged in. Everything is fine when I open Orange on the retina or only use an external screen. The problem happens when both screens are on, and I open orange on the external screen.

[ales-erjavec]

After checkout, these branch icons are oversized (see screenshot below). My setup is a laptop with a retina screen and an external "normal" screen plugged in.

Is this happening using Qt6?

[PrimozGodec]

Is this happening using Qt6?

Yes, I have PyQt6. I can also try it later on PyQt5.
Edit: I tested it with PyQt5, and the same error is also present.

[codecov-commenter]

Codecov Report

Patch coverage: 91.92% and project coverage change: +0.24 🎉

Comparison is base (ee765db) 75.06% compared to head (43b52f2) 75.30%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #271      +/-   ##
==========================================
+ Coverage   75.06%   75.30%   +0.24%     
==========================================
  Files          97       99       +2     
  Lines       20766    20953     +187     
==========================================
+ Hits        15588    15779     +191     
+ Misses       5178     5174       -4     

Impacted Files	Coverage Δ
orangecanvas/registry/discovery.py	38.28% <0.00%> (ø)
orangecanvas/registry/utils.py	93.65% <ø> (ø)
orangecanvas/document/quickmenu.py	68.76% <36.36%> (+0.02%)	⬆️
orangecanvas/resources.py	75.69% <77.77%> (-0.69%)	⬇️
orangecanvas/utils/image.py	92.45% <92.45%> (ø)
orangecanvas/gui/iconengine.py	96.11% <96.11%> (ø)
orangecanvas/gui/svgiconengine.py	90.85% <96.42%> (+6.47%)	⬆️
orangecanvas/application/application.py	61.72% <100.00%> (+0.47%)	⬆️
orangecanvas/application/canvastooldock.py	70.55% <100.00%> (+0.68%)	⬆️
orangecanvas/application/widgettoolbox.py	61.29% <100.00%> (-0.16%)	⬇️
... and 4 more

... and 3 files with indirect coverage changes

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[ales-erjavec]

Can you check again with the latest version.

[PrimozGodec]

Can you check again with the latest version.

It looks good now.