Ability to refresh OAuth2 token

Hi Santiago!
Thanks a lot for this very nice xdk for X API, I am really loving it!
Would it be possible to add a method to [refresh tokens](https://docs.x.com/fundamentals/authentication/oauth-2-0/authorization-code#refresh-tokens)
```ts
refreshTokens(refreshToken: string, clientID: string): Promise<OAuth2Token>
```