Pull diagnostics fixes (#32242)

Follow-up of https://github.com/zed-industries/zed/pull/19230

* starts to send `result_id` in pull requests to allow servers to reply
with non-full results
* fixes a bug where disk-based diagnostics were offset after pulling the
diagnostics
* fixes a bug due to which pull diagnostics could not be disabled
* uses better names and comments for the workspace pull diagnostics part

Release Notes:

- N/A

crates/project/src/lsp_store/clangd_ext.rs

@@ -84,6 +84,7 @@ pub fn register_notifications(
                     this.merge_diagnostics(
                         server_id,
                         mapped_diagnostics,
+                        None,
                         DiagnosticSourceKind::Pushed,
                         &adapter.disk_based_diagnostic_sources,
                         |diag, _| !is_inactive_region(diag),