[Feature]: Implement password grant type flow for OAuth2

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Summary

The password grant type is similar to client credentials in that their is no end user interaction while authenticating. However the authentication flow comes back with refresh tokens that can be used for creating valid access tokens once they expire.
Ref: https://www.oauth.com/oauth2-servers/access-tokens/password-grant/

### Why should this be worked on?

Users may have use cases that require them to connect to APIs that only have support for this deprecated grant type. We should enable this feature so that such APIs can also be connected to.