git: Amend (#28187)

Adds git amend support.

- [x] Turn existing commit button into split button
- [x] Clean up + Handle shortcuts/focus cases
- [x] Test remote

Release Notes:

- Added git amend support.

---------

Co-authored-by: Cole Miller <cole@zed.dev>

crates/git/src/git.rs

@@ -50,6 +50,8 @@ actions!(
         Pull,
         Fetch,
         Commit,
+        Amend,
+        Cancel,
         ExpandCommitEditor,
         GenerateCommitMessage,
         Init,

crates/git/src/repository.rs

@@ -74,6 +74,11 @@ impl Upstream {
     }
 }
 
+#[derive(Clone, Copy, Default)]
+pub struct CommitOptions {
+    pub amend: bool,
+}
+
 #[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
 pub enum UpstreamTracking {
     /// Remote ref not present in local repository.
@@ -252,6 +257,7 @@ pub trait GitRepository: Send + Sync {
         &self,
         message: SharedString,
         name_and_email: Option<(SharedString, SharedString)>,
+        options: CommitOptions,
         env: Arc<HashMap<String, String>>,
     ) -> BoxFuture<Result<()>>;
 
@@ -368,8 +374,8 @@ impl RealGitRepository {
 
 #[derive(Clone, Debug)]
 pub struct GitRepositoryCheckpoint {
-    ref_name: String,
-    commit_sha: Oid,
+    pub ref_name: String,
+    pub commit_sha: Oid,
 }
 
 impl GitRepository for RealGitRepository {
@@ -957,6 +963,7 @@ impl GitRepository for RealGitRepository {
         &self,
         message: SharedString,
         name_and_email: Option<(SharedString, SharedString)>,
+        options: CommitOptions,
         env: Arc<HashMap<String, String>>,
     ) -> BoxFuture<Result<()>> {
         let working_directory = self.working_directory();
@@ -969,6 +976,10 @@ impl GitRepository for RealGitRepository {
                     .arg(&message.to_string())
                     .arg("--cleanup=strip");
 
+                if options.amend {
+                    cmd.arg("--amend");
+                }
+
                 if let Some((name, email)) = name_and_email {
                     cmd.arg("--author").arg(&format!("{name} <{email}>"));
                 }
@@ -1765,6 +1776,7 @@ mod tests {
         repo.commit(
             "Initial commit".into(),
             None,
+            CommitOptions::default(),
             Arc::new(checkpoint_author_envs()),
         )
         .await
@@ -1793,6 +1805,7 @@ mod tests {
         repo.commit(
             "Commit after checkpoint".into(),
             None,
+            CommitOptions::default(),
             Arc::new(checkpoint_author_envs()),
         )
         .await