Proper dropdown active area and arrow placement

[Frizi]

Pull Request Description

Fixes #7423

Refactored widget matching algorithm to allow creating wrapper widgets even in cases where the widget config override is present. That allowed the widgets to be reordered, such that the argument name ends up being inside the dropdown widget. That way clicking it opens the dropdown.

Added explicit manual layout for the dropdown arrow position. Now it is positioned on the center of a selected appropriate child widget. For prefix chains, the leftmost part of the prefix application (the method or constructor) is selected.

dropdown-placement.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.

[vitvakatu]

I'm not much familiar with the code, but after reading it and the docs carefully I even understood most of the things there! Nice job with it. A few minor nitpicks.

[vitvakatu]

I don't understand the last sentence. They will take priority over what? What are the consequences of taking priority?
Also, the working of the second sentence is also confusing. I suggest to slightly rewrite it as follows:

Widgets that declare `true` here must create a child widget on the same span-tree node, so that the override can be applied to this child instead.

[Frizi]

I've added more docs explaining the implicit ordering and where it is defined.

[vitvakatu]

Shouldn't we also modify the Widget Configuration section in the module documentation, to mention this QUERY_ON_OVERRIDE const?

[Frizi]

Indeed, I've added a section there. Also changed the const name to PRIORITY_OVER_OVERRIDE, since the old one didn't really make any sense. The query word in never otherwise used in this context.

[MichaelMauderer]

QA: 🟢