Refactor timestamp formatting in Git UI components to use chrono for local time calculations (#41005)

- Updated `blame_ui.rs`, `branch_picker.rs`, `commit_tooltip.rs`, and
`commit_view.rs` to replace the previous timestamp formatting with
`chrono` for better accuracy in local time representation.
- Introduced `chrono::Local::now().offset().local_minus_utc()` to obtain
the local offset for timestamp formatting.

Closes #40878

Release Notes:
- Improved timestamp handling in various Git UI components for enhanced
user experience.

crates/git_ui/src/commit_view.rs

@@ -415,12 +415,14 @@ fn format_commit(commit: &CommitDetails, is_stash: bool) -> String {
         commit.author_name, commit.author_email
     )
     .unwrap();
+    let local_offset = time::UtcOffset::current_local_offset().unwrap_or(time::UtcOffset::UTC);
     writeln!(
         &mut result,
         "Date:   {}",
-        time_format::format_local_timestamp(
+        time_format::format_localized_timestamp(
             time::OffsetDateTime::from_unix_timestamp(commit.commit_timestamp).unwrap(),
             time::OffsetDateTime::now_utc(),
+            local_offset,
             time_format::TimestampFormat::MediumAbsolute,
         ),
     )