Batch diagnostics updates (#35794)

Diagnostics updates were programmed in Zed based off the r-a LSP push
diagnostics, with all related updates happening per file.

https://github.com/zed-industries/zed/pull/19230 and especially
https://github.com/zed-industries/zed/pull/32269 brought in pull
diagnostics that could produce results for thousands files
simultaneously.

It was noted and addressed on the local side in
https://github.com/zed-industries/zed/pull/34022 but the remote side was
still not adjusted properly.

This PR 

* removes redundant diagnostics pull updates on remote clients, as
buffer diagnostics are updated via buffer sync operations separately
* batches all diagnostics-related updates and proto messages, so
multiple diagnostic summaries (per file) could be sent at once,
specifically, 1 (potentially large) diagnostics summary update instead
of N*10^3 small ones.

Buffer updates are still sent per buffer and not updated, as happening
separately and not offending the collab traffic that much.

Release Notes:

- Improved diagnostics performance in the collaborative mode

crates/project/src/lsp_store/clangd_ext.rs

@@ -1,4 +1,4 @@
-use std::sync::Arc;
+use std::{borrow::Cow, sync::Arc};
 
 use ::serde::{Deserialize, Serialize};
 use gpui::WeakEntity;
@@ -6,7 +6,7 @@ use language::{CachedLspAdapter, Diagnostic, DiagnosticSourceKind};
 use lsp::{LanguageServer, LanguageServerName};
 use util::ResultExt as _;
 
-use crate::LspStore;
+use crate::{LspStore, lsp_store::DocumentDiagnosticsUpdate};
 
 pub const CLANGD_SERVER_NAME: LanguageServerName = LanguageServerName::new_static("clangd");
 const INACTIVE_REGION_MESSAGE: &str = "inactive region";
@@ -81,12 +81,16 @@ pub fn register_notifications(
                         version: params.text_document.version,
                         diagnostics,
                     };
-                    this.merge_diagnostics(
-                        server_id,
-                        mapped_diagnostics,
-                        None,
+                    this.merge_lsp_diagnostics(
                         DiagnosticSourceKind::Pushed,
-                        &adapter.disk_based_diagnostic_sources,
+                        vec![DocumentDiagnosticsUpdate {
+                            server_id,
+                            diagnostics: mapped_diagnostics,
+                            result_id: None,
+                            disk_based_sources: Cow::Borrowed(
+                                &adapter.disk_based_diagnostic_sources,
+                            ),
+                        }],
                         |_, diag, _| !is_inactive_region(diag),
                         cx,
                     )