feat: improve file diff for fs write

[brandonskiser]

Description of changes:

• Adding a file diff visualization for fs_write that displays line numbers. This implementation needs to be improved for truecolor support - currently, we don't highlight the entire document which can result in lines being highlighted incorrectly, consequently impacting the diff.
• Removing the clean_file_content function since it was resulting in a lot of errors with the model trying to use str_replace. Essentially, we were writing different content than the model was generating, which thus required it to constantly reread the file to see what we actually wrote.
• Moving the logic for appending a newline to a separate function shared by all fs_write commands.
• Fixed bug with append not including a newline at the end of the file.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 60.00000% with 112 lines in your changes missing coverage. Please review.
✅ Project coverage is 13.45%. Comparing base (b9d7bbc) to head (fda6e4a).
⚠️ Report is 829 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/q_cli/src/cli/chat/tools/fs_write.rs	59.78%	90 Missing and 21 partials ⚠️
crates/q_cli/src/cli/chat/tools/mod.rs	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #799      +/-   ##
==========================================
+ Coverage   13.42%   13.45%   +0.03%     
==========================================
  Files        2359     2359              
  Lines      203091   203141      +50     
  Branches   183455   183505      +50     
==========================================
+ Hits        27272    27342      +70     
+ Misses     174417   174383      -34     
- Partials     1402     1416      +14     

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[hsbakshi]

Is there a way we could remove the trailing whitespace that the model generates? It results in several checkstyle/lint errors as well as some people have editors that highlight them as errors.