Con-991-a: Diff Manager Improvements

[justinmilner1]

Description

Note: Work was started in this MR.
I started this new branch as the last one got messy.

This MR makes two improvements to vertical diff managers:

1) Open diffs are adjusted to user edits to the file

• A listener becomes active when a diff is opened, and will update the open diffs to user edits in the file

2) Sequentially opened diffs will be handled properly

• If a new diff is to be created while another one is open, the old diff will be properly closed, and the new diff properly initialized (fixes this bug)
• If the previous diff was created by ctrl-I, and no new selection has been made, the new diff will re-use the old diff selection
• If the previous diff was created by ctrl-I, and a new selection has been highlighted, the new diff will use the new selection

Test Evidence:

Accept all/Reject all

simplescreenrecorder-2024-04-27_22.41.48.mp4

Mixing individual accept/rejects and grouped accept/reject alls:

simplescreenrecorder-2024-04-27_22.42.50.mp4

With red:

simplescreenrecorder-2024-04-29_10.05.52.mp4

With user edits before and between blocks

simplescreenrecorder-2024-04-29_10.09.47.mp4

Attempt to open multiple diffs and only one is allowed at a time (and diff is created at correct (new) position)
Block above:

simplescreenrecorder-2024-04-29_16.52.05.mp4

Block below:

simplescreenrecorder-2024-04-29_13.10.58.mp4

Ctrl I (No new selection)

simplescreenrecorder-2024-04-27_22.46.52.mp4

Ctrl I (New selection)

simplescreenrecorder-2024-04-29_16.53.51.mp4