Add missing type exports

Author: acelaya

src/helpers/index.ts

@@ -1,2 +1,4 @@
-export type { Group, GroupType } from './groups';
 export { processAndReplaceMentionElements } from './mentions';
+
+export type { Group, GroupType } from './groups';
+export type { Mention, MentionMode, InvalidMentionContent } from './mentions';

src/index.ts

@@ -18,4 +18,10 @@ export type {
   MarkdownViewProps,
   MentionPopoverContentProps,
 } from './components';
-export type { Group, GroupType } from './helpers';
+export type {
+  Group,
+  GroupType,
+  Mention,
+  MentionMode,
+  InvalidMentionContent,
+} from './helpers';