User authentication and authorization

[aahnik]

Use local jwt based oauth + external oauth providers

• [ ] add email verification for local oauth
• [x] for external oauth providers: allow google + github
• [ ] use nests throttler, and enforce strict throttling for /auth/ endpoints
• [x] allow user to connect their google/github account in future, if they created account using email/password
• [ ] allow user to set password in future, if they created account with external oauth provider
• [ ] endpoint to reset password
• [ ] dto with validators/regex specifying, password quality