Execution environment integration fixes.

[MichaelMauderer]

Pull Request Description

Follow up to #6341 (comment) . Contains some refactoring and solves some left over to-dos in the code.

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]

QA Report 🔴

Shortcuts change the visual state of the dropdown but do not switch the execution environment. No messages to the engine and icons on nodes are not updated.

[MichaelMauderer]

QA Report red_circle

Shortcuts change the visual state of the dropdown but do not switch the execution environment. No messages to the engine and icons on nodes are not updated.

This was a bug ion the dropdown not updating its output when using the FRP API to override the selection. Urgh. Should be fixed now.

[vitvakatu]

QA Passed 🟢

[vitvakatu]

Fixed recently spotted an issue with the environment name in generated code and retested the whole thing.