WidgetFunction: merge dynamic config for a call with inherited one

[farmaazon]

Pull Request Description

Fixes #9008

Now, even if we inherit FunctionCall config from parent widget (e.g. drop down), we still ask for config of the current call and try to merge them (preferring the inherited parameters).

Important Notes

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.