Edit: Improve Rejection Tracker. Handle file deletions and formatters

[umpox]

Description

This PR:

• Improves how we track rejection for edit tasks
  • We now track when the file is deleted, before a change is made (important for cases like test or generate)
  • We now filter out multi-character changes, as these are likely to come from formatters or other commands. They are not a good signal that the user has made an implicit choice to accept this Edit.
  • We now filter out empty (whitespace) changes, as these are not a good signal that the user has made an implicit choice to continue coding and thus accept the edit
• Added lots of unit tests for the rejection tracker, so we can ensure this logic doesn't break over time

Test plan

Tested with unit tests, manual plan below:

Normal Edit - Rejected:

1. Make an Edit
2. Undo it
3. Make another change
4. Expected rejected

Normal Edit - Accepted

1. Make an edit
2. Make another change, type something
3. Expected accepted

Normal Edit - Empty changes - Accepted

1. Make an edit
2. Enter an empty change (e.g. new lines)
3. Expect not accepted or rejected
4. Make a single character change
5. Expect accepted

Normal Edit - Empty changes - Rejected

1. Make an edit
2. Make another change
3. Enter an empty change (e.g. new lines)
4. Expect not accepted or rejected
5. Undo the change
6. Expect nothing happened (undone empty change)
7. Undo the change again
8. Expect rejected

Normal Edit - Large changes - Accepted

1. Make an edit
2. Paste multiple characters of text (simulate something like a formatter)
3. Expect not accepted or rejected
4. Make a single character change
5. Expect accepted

Normal Edit - Large changes - Rejected

1. Make an edit
2. Paste multiple characters of text (simulate something like a formatter)
3. Expect not accepted or rejected
4. Undo the change
5. Expect nothing happened (undone empty change)
6. Undo the change again
7. Expect rejected

[umpox]

@abeatrix For the unit test one in particular, here's some additional testing:

• If the file is unsaved, and then closed we log rejected
• If the file is saved, we don't log anything
• If the user makes a change to the file, we log accepted
• If the user clicks "Undo" on the test change in the file, we log rejected

[philipp-spiess]

Love this! Especially the tests are :chef-kiss: