git: Hard wrap in editor (#26507)

This adds the ability for the editor to implement hard wrap (similar to
"textwidth" in vim).

If you are typing and your line extends beyond the limit, a newline is
inserted before the most recent space on the line. If you are otherwise
editing the line, pasting, etc. then you will need to manually rewrap.

Release Notes:

- git: Commit messages are now wrapped "as you type" to 72 characters.

crates/git_ui/src/git_panel.rs

@@ -367,6 +367,7 @@ pub(crate) fn commit_message_editor(
     commit_editor.set_show_gutter(false, cx);
     commit_editor.set_show_wrap_guides(false, cx);
     commit_editor.set_show_indent_guides(false, cx);
+    commit_editor.set_hard_wrap(Some(72), cx);
     let placeholder = placeholder.unwrap_or("Enter commit message");
     commit_editor.set_placeholder_text(placeholder, cx);
     commit_editor