[FE]: Consolidate the Edit and Web IDE buttons into a single split dropdown
This is a frontend part of the implementation, described in #221247 (closed).
The design description: #221247 (closed)
This issue is responsible for:
- On the File (/-/blob/branch/file) page replace the Edit and Web IDE button with a [split dropdown]. (https://design.gitlab.com/components/button#split-dropdown)
- Default button to Edit in Web IDE
- Clicking the attached dropdown button opens a dropdown with options to set the default button action
- Edit in Web IDE
- Edit file
- Additional options
- Clicking the button should load the Web IDE/Single file editor/Other based on the chosen option
- Option choice should be persisted
!Important! The picked option in the dropdown should be stored in the localStorage. But this might be already implemented in !37985 (merged) by the time this issue is taken care of.
Edited by Denys Mishunov