Rework shared commit editors (#24274)

Rework of https://github.com/zed-industries/zed/pull/24130
Uses
https://github.com/d1y/git_firefly/tree/1033c0b57ec88a002cb68efc64c8d9bf5c212e30
`COMMIT_EDITMSG` language-related definitions (thanks @d1y )

Instead of using real `.git/COMMIT_EDITMSG` file, create a buffer
without FS representation, stored in the `Repository` and shared the
regular way via the `BufferStore`.
Adds a knowledge of what `Git Commit` language is, and uses it in the
buffers which are rendered in the git panel.


Release Notes:

- N/A

---------

Co-authored-by: Conrad Irwin <conrad@zed.dev>
Co-authored-by: d1y <chenhonzhou@gmail.com>
Co-authored-by: Smit <smit@zed.dev>

crates/git/src/repository.rs

@@ -1,6 +1,6 @@
 use crate::status::FileStatus;
+use crate::GitHostingProviderRegistry;
 use crate::{blame::Blame, status::GitStatus};
-use crate::{GitHostingProviderRegistry, COMMIT_MESSAGE};
 use anyhow::{anyhow, Context as _, Result};
 use collections::{HashMap, HashSet};
 use git2::BranchType;
@@ -68,7 +68,7 @@ pub trait GitRepository: Send + Sync {
     /// If any of the paths were previously staged but do not exist in HEAD, they will be removed from the index.
     fn unstage_paths(&self, paths: &[RepoPath]) -> Result<()>;
 
-    fn commit(&self, name_and_email: Option<(&str, &str)>) -> Result<()>;
+    fn commit(&self, message: &str, name_and_email: Option<(&str, &str)>) -> Result<()>;
 }
 
 impl std::fmt::Debug for dyn GitRepository {
@@ -298,22 +298,14 @@ impl GitRepository for RealGitRepository {
         Ok(())
     }
 
-    fn commit(&self, name_and_email: Option<(&str, &str)>) -> Result<()> {
+    fn commit(&self, message: &str, name_and_email: Option<(&str, &str)>) -> Result<()> {
         let working_directory = self
             .repository
             .lock()
             .workdir()
             .context("failed to read git work directory")?
             .to_path_buf();
-        let commit_file = self.dot_git_dir().join(*COMMIT_MESSAGE);
-        let commit_file_path = commit_file.to_string_lossy();
-        let mut args = vec![
-            "commit",
-            "--quiet",
-            "-F",
-            commit_file_path.as_ref(),
-            "--cleanup=strip",
-        ];
+        let mut args = vec!["commit", "--quiet", "-m", message, "--cleanup=strip"];
         let author = name_and_email.map(|(name, email)| format!("{name} <{email}>"));
         if let Some(author) = author.as_deref() {
             args.push("--author");
@@ -480,7 +472,7 @@ impl GitRepository for FakeGitRepository {
         unimplemented!()
     }
 
-    fn commit(&self, _name_and_email: Option<(&str, &str)>) -> Result<()> {
+    fn commit(&self, _message: &str, _name_and_email: Option<(&str, &str)>) -> Result<()> {
         unimplemented!()
     }
 }