Add the option to treat the viewer file as master

[tapple]

Added a new information popup when a file is edited that matches a master file and has differences:

The options are hopefully self-explanatory:

• Ignore or X: do nothing (same behavior as before)
• Overwrite master: apply all changes in the viewer file to the master file
• Compare: Open viewer file and master file in a diff editor for auditing or merging
• Always ignore: Ignore and set a workspace-level preference to always ignore

This makes the plugin easier to use for simple users like me who:

• mostly code in the viewer
• Don't use require() or the preprocessor

but still want to use the plugin for:

• easy archival to git
• luau type-checking and linting
• another editor option