feat: Automatic invite reminder email (#3354)

* feat: Add user flags concept, for tracking bits on a user

* feat: Example flag usage for user invite resend abuse

* wip

* test

* fix: Set correct flag

server/test/factories.ts

@@ -161,12 +161,16 @@ export async function buildInvite(overrides: Partial<User> = {}) {
     overrides.teamId = team.id;
   }
 
+  const actor = await buildUser({ teamId: overrides.teamId });
+
   count++;
   return User.create({
     email: `user${count}@example.com`,
     name: `User ${count}`,
     createdAt: new Date("2018-01-01T00:00:00.000Z"),
+    invitedById: actor.id,
     ...overrides,
+    lastActiveAt: null,
   });
 }