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_command.rs

@@ -3832,7 +3832,7 @@ impl LspCommand for GetDocumentDiagnostics {
     fn to_lsp(
         &self,
         path: &Path,
-        _: &Buffer,
+        buffer: &Buffer,
         language_server: &Arc<LanguageServer>,
         _: &App,
     ) -> Result<lsp::DocumentDiagnosticParams> {
@@ -3849,7 +3849,7 @@ impl LspCommand for GetDocumentDiagnostics {
                 uri: file_path_to_lsp_url(path)?,
             },
             identifier,
-            previous_result_id: None,
+            previous_result_id: buffer.result_id(),
             partial_result_params: Default::default(),
             work_done_progress_params: Default::default(),
         })