[FRONTEND] Add feedback for booking creation success

[bcho892]

Is your feature request related to a problem? Please describe. Right now it remains open which is ok, but need some feedback.

This is for the AdminBookingView:

We need to add an alert so that the admin knows if the selected user has actually been added to the booking or not.

change at client\src\components\composite\Admin\AdminBookingView\WrappedAdminBookingCreationPopUp.tsx

BEFORE MERGING

• [ ] Storybooks created where possible
• [ ] Tested with nock if data fetching
• [ ] Tests written for critical interactions
• [ ] PR Reviewed (For non-trivial changes)
• [ ] Changes tested after rebasing on master or merging in master (hint: git fetch origin master:master, then git rebase master or git merge master)
• [ ] All required PR checks passing