Fix remote clients unable to query custom, lsp_ext, commands (#27775)

Closes https://github.com/zed-industries/zed/issues/20583
Closes https://github.com/zed-industries/zed/issues/27133

A preparation for rust-analyzer's LSP tasks fetching, ensures all remote
clients are able to query custom, lsp_ext, commands.

Release Notes:

- Fixed remote clients unable to query custom, lsp_ext, commands

crates/proto/proto/zed.proto

@@ -361,7 +361,10 @@ message Envelope {
         RemoveRepository remove_repository = 329;
 
         GetDocumentSymbols get_document_symbols = 330;
-        GetDocumentSymbolsResponse get_document_symbols_response = 331; // current max
+        GetDocumentSymbolsResponse get_document_symbols_response = 331;
+
+        LanguageServerIdForName language_server_id_for_name = 332;
+        LanguageServerIdForNameResponse language_server_id_for_name_response = 333; // current max
     }
 
     reserved 87 to 88;
@@ -3567,3 +3570,13 @@ message GitInit {
     string abs_path = 2;
     string fallback_branch_name = 3;
 }
+
+message LanguageServerIdForName {
+    uint64 project_id = 1;
+    uint64 buffer_id = 2;
+    string name = 3;
+}
+
+message LanguageServerIdForNameResponse {
+    optional uint64 server_id = 1;
+}

crates/proto/src/proto.rs

@@ -302,6 +302,8 @@ messages!(
     (GetImplementationResponse, Background),
     (GetLlmToken, Background),
     (GetLlmTokenResponse, Background),
+    (LanguageServerIdForName, Background),
+    (LanguageServerIdForNameResponse, Background),
     (OpenUnstagedDiff, Foreground),
     (OpenUnstagedDiffResponse, Foreground),
     (OpenUncommittedDiff, Foreground),
@@ -580,6 +582,7 @@ request_messages!(
     (UpdateWorktree, Ack),
     (UpdateRepository, Ack),
     (RemoveRepository, Ack),
+    (LanguageServerIdForName, LanguageServerIdForNameResponse),
     (LspExtExpandMacro, LspExtExpandMacroResponse),
     (LspExtOpenDocs, LspExtOpenDocsResponse),
     (SetRoomParticipantRole, Ack),
@@ -714,6 +717,7 @@ entity_messages!(
     OpenServerSettings,
     GetPermalinkToLine,
     LanguageServerPromptRequest,
+    LanguageServerIdForName,
     GitGetBranches,
     UpdateGitBranch,
     ListToolchains,