Add support for short mentions from ExpensiMark (Expensify#592)

Author: Kicu

src/commonTypes.ts

@@ -5,6 +5,7 @@ type MarkdownType =
   | 'emoji'
   | 'mention-here'
   | 'mention-user'
+  | 'mention-short'
   | 'mention-report'
   | 'link'
   | 'code'

src/parseExpensiMark.ts

@@ -155,6 +155,8 @@ function parseTreeToTextAndRanges(tree: StackItem): [string, MarkdownRange[]] {
         addChildrenWithStyle(node, 'mention-here');
       } else if (node.tag === '<mention-user>') {
         addChildrenWithStyle(node, 'mention-user');
+      } else if (node.tag === '<mention-short>') {
+        addChildrenWithStyle(node, 'mention-short');
       } else if (node.tag === '<mention-report>') {
         addChildrenWithStyle(node, 'mention-report');
       } else if (node.tag === '<blockquote>') {