git: Enable git stash in git panel (#32821)

Related discussion #31484

Release Notes:

- Added a menu entry on the git panel to git stash and git pop stash. 

Preview: 


![Screenshot-2025-06-17_08:26:36](https://github.com/user-attachments/assets/d3699ba4-511f-4c7b-a7cc-00a295d01f64)

---------

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

crates/proto/proto/git.proto

@@ -286,6 +286,17 @@ message Unstage {
     repeated string paths = 4;
 }
 
+message Stash {
+    uint64 project_id = 1;
+    uint64 repository_id = 2;
+    repeated string paths = 3;
+}
+
+message StashPop {
+    uint64 project_id = 1;
+    uint64 repository_id = 2;
+}
+
 message Commit {
     uint64 project_id = 1;
     reserved 2;

crates/proto/proto/zed.proto

@@ -396,8 +396,10 @@ message Envelope {
         GetDocumentColor get_document_color = 353;
         GetDocumentColorResponse get_document_color_response = 354;
         GetColorPresentation get_color_presentation = 355;
-        GetColorPresentationResponse get_color_presentation_response = 356; // current max
+        GetColorPresentationResponse get_color_presentation_response = 356;
 
+        Stash stash = 357;
+        StashPop stash_pop = 358; // current max
     }
 
     reserved 87 to 88;

crates/proto/src/proto.rs

@@ -261,6 +261,8 @@ messages!(
     (Unfollow, Foreground),
     (UnshareProject, Foreground),
     (Unstage, Background),
+    (Stash, Background),
+    (StashPop, Background),
     (UpdateBuffer, Foreground),
     (UpdateBufferFile, Foreground),
     (UpdateChannelBuffer, Foreground),
@@ -419,6 +421,8 @@ request_messages!(
     (TaskContextForLocation, TaskContext),
     (Test, Test),
     (Unstage, Ack),
+    (Stash, Ack),
+    (StashPop, Ack),
     (UpdateBuffer, Ack),
     (UpdateParticipantLocation, Ack),
     (UpdateProject, Ack),
@@ -549,6 +553,8 @@ entity_messages!(
     TaskContextForLocation,
     UnshareProject,
     Unstage,
+    Stash,
+    StashPop,
     UpdateBuffer,
     UpdateBufferFile,
     UpdateDiagnosticSummary,