Start on a Git-based review flow (#27103)

Release Notes:

- N/A

---------

Co-authored-by: Nathan Sobo <nathan@zed.dev>

Cargo.lock

@@ -467,6 +467,7 @@ dependencies = [
  "futures 0.3.31",
  "fuzzy",
  "git",
+ "git_ui",
  "gpui",
  "heed",
  "html_to_markdown",
@@ -5601,11 +5602,13 @@ dependencies = [
  "serde_json",
  "smol",
  "sum_tree",
+ "tempfile",
  "text",
  "time",
  "unindent",
  "url",
  "util",
+ "uuid",
 ]
 
 [[package]]