Allow LSP adapters to decide, which diagnostics to underline (#31450)

Closes
https://github.com/zed-industries/zed/pull/31355#issuecomment-2910439798

<img width="1728" alt="image"
src="https://github.com/user-attachments/assets/2eaa8e9b-00bc-4e99-ac09-fceb2d932e41"
/>


Release Notes:

- N/A

crates/project/src/lsp_store.rs

@@ -8782,6 +8782,10 @@ impl LspStore {
                 .as_ref()
                 .map_or(false, |tags| tags.contains(&DiagnosticTag::UNNECESSARY));
 
+            let underline = self
+                .language_server_adapter_for_id(language_server_id)
+                .map_or(true, |adapter| adapter.underline_diagnostic(diagnostic));
+
             if is_supporting {
                 supporting_diagnostics.insert(
                     (source, diagnostic.code.clone(), range),
@@ -8814,6 +8818,7 @@ impl LspStore {
                         is_primary: true,
                         is_disk_based,
                         is_unnecessary,
+                        underline,
                         data: diagnostic.data.clone(),
                     },
                 });
@@ -8839,6 +8844,7 @@ impl LspStore {
                                     is_primary: false,
                                     is_disk_based,
                                     is_unnecessary: false,
+                                    underline,
                                     data: diagnostic.data.clone(),
                                 },
                             });

crates/project/src/lsp_store/clangd_ext.rs

@@ -37,6 +37,15 @@ pub fn is_inactive_region(diag: &Diagnostic) -> bool {
             .is_some_and(|v| v == CLANGD_SERVER_NAME)
 }
 
+pub fn is_lsp_inactive_region(diag: &lsp::Diagnostic) -> bool {
+    diag.severity == Some(INACTIVE_DIAGNOSTIC_SEVERITY)
+        && diag.message == INACTIVE_REGION_MESSAGE
+        && diag
+            .source
+            .as_ref()
+            .is_some_and(|v| v == CLANGD_SERVER_NAME)
+}
+
 pub fn register_notifications(
     lsp_store: WeakEntity<LspStore>,
     language_server: &LanguageServer,