Add Functionalities to Send Invitation Modal

[nhatnghiho]

Description

Now that we have the InvitationModal for users to invite friends to view their schedules via email, we want to add functionalities to this modal. This includes:

1. Update the ScheduleData schema to include the list of invited friends and the status of the invitation.
2. Fetch the set of recently invited friends and incorporate those into the autocomplete function.
3. Enable the Send Invite button to trigger the send email cloud function on click.
4. On send success or failure, display the correct feedback.
5. Add the invited friend's into ScheduleData as Pending invitation once an email is sent successfully.
6. Change the status of the invited friend to Accepted once they click on the confirmation link in the invitation email.
7. Display the list of invited friends and their invitation statuses on the modal.

Steps 1-4 and 7 should be done in the gt-scheduler/website repo; steps 5-6 should be done in Cloud Functions in the gt-scheduler/firebase-conf repo.

Acceptance Criteria

• ScheduleData is updated to include the list of invited friends and the status of the invitation.
  • migrateScheduleData must be updated along with any related tests.
• Autocomplete displays emails of recently invited friends from the last 3 semesters.
• Search results are displayed based on what the user has typed in.
• Emails are sent and feedback is displayed to the user appropriately.
• Status of invitation is updated appropriately.
• List of invited friends is displayed appropriately.

Other Notes

• I'd recommend the following for adding friends to ScheduleData, particularly to the ScheduleVersion subtype:

{
   name: string;
   createdAt: string;
   ...,
   friends: {
       _FRIEND_ID_: {
           status: 'Accepted' | 'Pending',
      }
   }
}