Debug Mode for Graph Editor

[vitvakatu]

Pull Request Description

Task link.

This PR adds an implementation of Debug Mode for Graph Editor. In this mode, a few special actions are available (they are marked with debug_mode condition in the Graph Editor shortcuts list). In the future, we would add more such actions (for example, node zooming with levels more than 1.0 will be available in debug mode only).

Debug Mode is toggled by pressing ctrl + shift + d key combination. The task mentioned ctrl + shift + alt + d, but apparently, such a combination does not work for me (probably hardware reasons).

A label on top of the screen signals that debug mode was enabled/disabled.

2022-02-10.14-39-03.mp4

Important Notes

Checklist

Please include the following checklist in your PR:

• The documentation has been updated if necessary.
• All code conforms to the Scala, Java, and Rust style guides.
• All documentation and configuration conforms to the markdown and YAML style guides.
• All code has been tested where possible.

[farmaazon]

Please refactor the Popup constructor a little, so it will be consistent with other visual components we have (see comments for details).