API keys support on the backend

[titanventura]

Fixes #360 partially

Changes made

• Added a table for API Keys
• added routes for users to be able to manage their API keys
• added a middleware to authenticate routes using API keys
• use the middleware for GET method of /api/watched endpoint

[titanventura]

@IRHM , please go through the updated PR. Thanks !

[IRHM]

Hi @titanventura, I'm happy to get this merged. Thanks for the good work!

There are a few minor things, but It's probably best I do them after deciding how the UI will work so it isn't wasted effort incase it needs changing.

Thanks!