git: Add ability to clone remote repositories from Zed (#35606)

This PR adds preliminary git clone support through using the new
`GitClone` action. This works with SSH connections too.

- [x] Get backend working
- [x] Add a UI to interact with this

Future follow-ups:
- Polish the UI
- Have the path select prompt say "Select Repository clone target"
instead of “Open”
- Use Zed path prompt if the user has that as a setting
- Add support for cloning from a user's GitHub repositories directly

Release Notes:

- Add the ability to clone remote git repositories through the `git:
Clone` action

---------

Co-authored-by: hpmcdona <hayden_mcdonald@brown.edu>

crates/proto/proto/git.proto

@@ -202,6 +202,16 @@ message GitInit {
     string fallback_branch_name = 3;
 }
 
+message GitClone {
+    uint64 project_id = 1;
+    string abs_path = 2;
+    string remote_repo = 3;
+}
+
+message GitCloneResponse {
+    bool success = 1;
+}
+
 message CheckForPushedCommits {
     uint64 project_id = 1;
     reserved 2;

crates/proto/proto/zed.proto

@@ -399,7 +399,10 @@ message Envelope {
         GetDefaultBranchResponse get_default_branch_response = 360;
 
         GetCrashFiles get_crash_files = 361;
-        GetCrashFilesResponse get_crash_files_response = 362; // current max
+        GetCrashFilesResponse get_crash_files_response = 362;
+
+        GitClone git_clone = 363;
+        GitCloneResponse git_clone_response = 364; // current max
     }
 
     reserved 87 to 88;