git: Unify commit popups (#38749)

Closes #26424
Supersedes #35328

Originally, `git::blame` uses its own `ParsedCommitMessage` as the
source for the commit information, including the PR section. This
changes unifies this with `git::repository` and `git_ui::git_panel` by
moving this and some other commit-related structs to `git::commit`
instead, and making both `git_ui::blame_ui` and `git_ui::git_panel` pull
their information from these structs.

Release notes :

- (Let's Git Together) Fixed the commit tooltip in the git panel not
showing information like avatars.

---------

Co-authored-by: Cole Miller <cole@zed.dev>
Co-authored-by: Zed Zippy <234243425+zed-zippy[bot]@users.noreply.github.com>

crates/git_ui/src/commit_tooltip.rs

@@ -3,7 +3,7 @@ use editor::hover_markdown_style;
 use futures::Future;
 use git::blame::BlameEntry;
 use git::repository::CommitSummary;
-use git::{GitRemote, blame::ParsedCommitMessage};
+use git::{GitRemote, commit::ParsedCommitMessage};
 use gpui::{
     App, Asset, ClipboardItem, Element, Entity, MouseButton, ParentElement, Render, ScrollHandle,
     StatefulInteractiveElement, WeakEntity, prelude::*,