[BACKEND] Create endpoint to create booking(s)

[bcho892]

Is your feature request related to a problem? Please describe.

[!WARNING] Needs to be scoped to admin users only

Is used for if admins want to manually add bookings.

Should take user uids in the form of an array as the request body

e.g

{ 
    startDate: Timestamp,
    endDate: Timestamp,
    users: string[]
}

BEFORE MERGING

• [ ] Integration test written for services
• [ ] Schemas annotated if adding new models
• [ ] Code generation run (hint: yarn workspace server tsoa spec-and-routes)
• [ ] Appropriate mocks created where possible
• [ ] 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