Start to split out initialization and registration (#21787)

Still TODO:

* [x] Factor out `start_language_server` so we can call it on register
(instead of on detect language)
* [x] Only call register in singleton editors (or when
editing/go-to-definition etc. in a multibuffer?)
* [x] Refcount on register so we can unregister when no buffer remain
* [ ] (maybe) Stop language servers that are no longer needed after some
time

Release Notes:

- Fixed language servers starting when doing project search
- Fixed high CPU usage when ignoring warnings in the diagnostics view

---------

Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>
Co-authored-by: Cole <cole@zed.dev>

crates/proto/proto/zed.proto

@@ -304,7 +304,9 @@ message Envelope {
         InstallExtension install_extension = 287;
 
         GetStagedText get_staged_text = 288;
-        GetStagedTextResponse get_staged_text_response = 289; // current max
+        GetStagedTextResponse get_staged_text_response = 289;
+
+        RegisterBufferWithLanguageServers register_buffer_with_language_servers = 290;
     }
 
     reserved 87 to 88;
@@ -2537,7 +2539,6 @@ message UpdateGitBranch {
     string branch_name = 2;
     ProjectPath repository = 3;
 }
-
 message GetPanicFiles {
 }
 
@@ -2582,3 +2583,8 @@ message InstallExtension {
     Extension extension = 1;
     string tmp_dir = 2;
 }
+
+message RegisterBufferWithLanguageServers{
+    uint64 project_id = 1;
+    uint64 buffer_id = 2;
+}

crates/proto/src/proto.rs

@@ -373,6 +373,7 @@ messages!(
     (SyncExtensions, Background),
     (SyncExtensionsResponse, Background),
     (InstallExtension, Background),
+    (RegisterBufferWithLanguageServers, Background),
 );
 
 request_messages!(
@@ -499,6 +500,7 @@ request_messages!(
     (CancelLanguageServerWork, Ack),
     (SyncExtensions, SyncExtensionsResponse),
     (InstallExtension, Ack),
+    (RegisterBufferWithLanguageServers, Ack),
 );
 
 entity_messages!(
@@ -584,6 +586,7 @@ entity_messages!(
     ActiveToolchain,
     GetPathMetadata,
     CancelLanguageServerWork,
+    RegisterBufferWithLanguageServers,
 );
 
 entity_messages!(