Require admin authorization on registrations getAll

[voctory]

Changes

• Add Cognito authorization to /registrations GET endpoint for case where we get all registrations for an event

Notes

• Message Victor for change justification
• This change breaks the Companion's use of the /registrations GET endpoint - follow-up PR on this repo will add API endpoints for Companion use
• This change breaks bt-web-v2's Registration table because of permission errors - follow-up PR on bt-web-v2 will fix this

Testing

Changes work on bt-web Admin registration table, not expected to break other Registrations microservice endpoints

[kevinxiao27]

LGTM!

Was the registration endpoint used for anything not gated? I agree that there should probably be auth required given the nature of the data we're fetching.

[voctory]

Answered offline

Will merge in this PR after we get the Companion Registration service up