Refactor birthday to use database instead of the spreadsheet.

[Pierre-Demessence]

For now the birthday features (!bday command and the BirthdayReminder Service) use a Google Sheet which is fed by a Google Form.
It would be better if people could add their birthday directly through the bot, with a command, if the birthday was stored in the database.
The bot should have these commands:

• Set own birthday (can redo to change birthday)
• Remove own birthday

Current features should continue to work the same way, but use the new data source instead of the Google Sheet.
One difference though: The birthday announcement feature should mention the user whose birthday is today. (But not the !bday command)

[hariedo]

Where possible, store the Discord userID in the database, not just the username or current display name. The display/command module should convert those to the preferred display name.

[edit: I now see the Copilot solution is using the same database as all other profile data, so it's definitely by userID. my comments are now just about the task of migration.]

Example, the birthday spreadsheet has two entries for Acey and actuallyacey.

Our profile database already has usernames and userIDs so most of the users so many of the spreadsheet entries can be migrated to userIDs.

If I had write permission on the spreadsheet I could add a userID column to get the migration ball rolling.