EE: Add the ability to restrict the user roles that can send team invites (#3442)

webapp/utils/constants.jsx

@@ -755,5 +755,8 @@ export default {
     MAX_PREV_MSGS: 100,
     POST_COLLAPSE_TIMEOUT: 1000 * 60 * 5, // five minutes
     LICENSE_EXPIRY_NOTIFICATION: 1000 * 60 * 60 * 24 * 15, // 15 days
-    LICENSE_GRACE_PERIOD: 1000 * 60 * 60 * 24 * 15 // 15 days
+    LICENSE_GRACE_PERIOD: 1000 * 60 * 60 * 24 * 15, // 15 days
+    TEAM_INVITE_ALL: 'all',
+    TEAM_INVITE_TEAM_ADMIN: 'team_admin',
+    TEAM_INVITE_SYSTEM_ADMIN: 'system_admin'
 };