Add User Donation Keys

[MrPowerGamerBR]

Fixes #2310

Stuff that needs to be checked and implemented:

• Route to get the user's donation keys
• Add a page to allow enabling/disabling user donation keys (just like the guild donation keys)
• +botinfo command still uses the Payments table
• DailyTaxTask uses the Payments table to check if the user needs to renew a donation
• LorittaLandRoleSync uses the Payments table to give the user's role
• Boost stuff needs to be fixed: Give a user donation key instead of adding a payment
• Give user donation key when buying premium

[MrPowerGamerBR]

For now this is on hold because I hate messing with the frontend (#2226)