Enhancement: Allow server options for automatic resolution of "Local cache of version exists" dialog

[Sasbom]

This PR adds a server option for automatically resolving the dialog that pops up when a newer, locally cached file is present.
This allows TDs setting up the plugin to be strict about there source of truth, instead of leaving it to the artist.
The PR was set up following a discussion within the community about this dialog's choice leaving a workflow vulnerable to loss of work.

The new options are disabled by default, and without enabling the "Force cache conflict source" option, in "Cache conflict resolution", the dialog will still pop up.

Thanks for your consideration,

Sas van Gulik

Changelog Description

This PR adds a server-side toggle + enum with corresponding options found in the "Local cache of version exists" dialog's buttons.
It allows the user to set a default strategy if that is wanted.
A server for fetching server options have been added to the clients api/lib.py.

Additional review information

I'm still not quite sure about the names of the options. That could be clearer, but I think this gets the points across.

Testing notes:

1. Include the plugin built with this branch in a bundle
2. Set "Cache conflict resolution" settings.
3. Launch Harmony with a known project that would give the "Local cache of version exists" dialog on startup, and see if expected changes are reflected.

[kalisp]

Could you please resolve conversation to mark that next round of testing/review should happen?

[Sasbom]

Could you please resolve conversation to mark that next round of testing/review should happen?

Done! Excuse my etiquette. Thanks for the reminder.