fix: remove blob::GitDiff Sink as it doesn't work concistently. (#2011)

Against better judgement I was compelled to merge this implementation in,
assuming one test must be enough given that it is a transcription.

This, however, wasn't the case and there is strong evidence that it produces
diffs that aren't correct.

Author: Byron

gix-diff/src/blob/git_diff.rs

@@ -14,9 +14,6 @@ pub mod platform;
 pub mod unified_diff;
 pub use unified_diff::_impl::UnifiedDiff;
 
-pub mod git_diff;
-pub use git_diff::types::GitDiff;
-
 /// Information about the diff performed to detect similarity.
 #[derive(Debug, Default, Clone, Copy, PartialEq, PartialOrd)]
 pub struct DiffLineStats {