[FEATURE] Allow using external diff tool for binary files

[miguelsguedeshpp]

1. Background

At the moment this always uses VS Code to compare two commits of a file, which works great for text based files - not so great for any binary files kept in the repo

2. Proposed Solution

Add an option to the context menu to allow user to open with external diff tool.

Something like this (from a different extension):

3. Affected Area

Check all that apply.

• Commit graph (Graph View)
• Commit details panel (Bottom Panel)
• Sidebar (Branches / Remotes / Tags / Stashes / Worktrees)
• Toolbar (Fetch / Pull / Push / Refresh)
• Context menu
• Search
• Statistics view (Stats)
• Activity Log
• i18n (localization)
• Git operations (new Git command support)
• Other

4. Alternatives or References

This is available in the GitLens extension for VS Code, with paid subscription