Color picker

[vitvakatu]

Pull Request Description

Closes #8680

The color picker is triggered by new Circular menu item or by keyboard shortcut (set to Mod+Shift+C for Color).
The color picker affects selected nodes, so it works nicely both in cases when we use Circular menu on a single node a shortcut with multiple selected nodes.

Color is only changed when the user selects a new one inside the color picker, but there is no specific way to reset default color (you would have to recreate the node).

changing.node.colors.mp4

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• Screenshots/screencasts have been attached, if there are any visual changes. For interactive or animated visual changes, a screencast is preferred.
• All code follows the
  Scala,
  Java,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• All code has been tested:
  • Unit tests have been written where possible.
  • If GUI codebase was changed, the GUI was tested when built using ./run ide build.