[RegistryPreview] Adopt Monaco Editor (#35122)

src/Monaco/customLanguages/gitignore.js

@@ -0,0 +1,13 @@
+export function gitignoreDefinition() {
+    return {
+        defaultToken: 'invalid',
+
+        tokenizer: {
+            root: [
+                [/^#.*$/, 'comment'],
+                [/.*((?<!(^|\/))\*\*.*|\*\*(?!(\/|$))).*/, 'invalid'],
+                [/((?:^!\s*(?:\\\s|\S)+)?)((?:^\s*(?:\\\s|\S)+)?)((?:\s+(?:\\\s|\S)+)*)/, ['custom-gitignore.negation', 'tag', 'invalid']]
+            ]
+        }
+    };
+}