Handle file renaming

[VeryMilkyJoe]

Adds handling of WillRenameFile Notification to the rename plugin.

When receiving this notification, we:

• change the module name to the new file name in the module declaration of the renamed file, and
• change all imports of the renamed file to the new name.

Note that in the example below, there are errors after renaming because we do not edit the cabal file so the project will not build after a rename.

This is part of the implementation of #4951.

Screencast.From.2026-06-07.15-09-27.mp4

[dyniec]

Looks good.
Could use small test like: Foo imports Bla, Bla is renamed to Bar, and check that now Foo imports Bar, and Bar is Bar.

Now that #4961 is merged those squiggles in demo would disappear?

[VeryMilkyJoe]

Looks good. Could use small test like: Foo imports Bla, Bla is renamed to Bar, and check that now Foo imports Bar, and Bar is Bar.

Now that #4961 is merged those squiggles in demo would disappear?

Yes, I am planning to add tests still!

The squiggles are due to the session not being reloaded, I plan to open the next PR, which reloads the session after a rename has been completed, after this one.