Added toolbar menu to export and import dock sets with recent dockset…

[dcmouser]

Added toolbar submenu for exporting and importing docksets (configuration files containing layout of docks), as well as a recent dockset list.

Description

Added new submenu under Docks to allow user to export and import docksets (saved configurations of docks), along with a recent dockset list. This makes it easy to save configurations of docks (where they are, which ones are visible, etc.). Very lightweight, uses the built-in dock saving and loading code in OBS.

Motivation and Context

Lots of requests for this over the years.

How Has This Been Tested?

Tested on windows OBS version 27 and 28.

Types of changes

New feature (non-breaking change which adds functionality)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[dcmouser]

Video demonstration:
https://www.youtube.com/watch?v=ABh49qwJGqQ

[Fenrirthviti]

As a note, we have an open RFC which is being strongly considered to move to a new docking system (ADS):

obsproject/rfcs#47

If we decide to accept this RFC, it would mean that this functionality would need to be replaced, and won't be compatible. However, switching to ADS will break existing dock setups anyway even without saving of layouts, so this may or may not be a blocker depending on how far away the ADS implementation is likely to be, or if it's accepted in the first place.

For the time being, let's evaluate this PR with the assumption that ADS is not on the table since merging this would more or less be unrelated, and would just be something implemented as part of ADS (so this would be removed at this time).

[dcmouser]

@Fenrirthviti That seems very reasonable. This code is very un-intrusive to the base code, and the minor menu additions could be adapted to a future dock system and the menu code for import/export and showing recent dock set files will all still be useful.

I feel like the ability to save and load dock configurations could be useful while waiting for any proposed new dock system. And I hope it will help the new dock system coders see that loading and saving dock configurations is an important feature to implemented in any new system.

[Warchamp7]

There was some relevant discussion on this idea previously in #2198