Add a way to refresh token

As per #54 , this package should have a way for people to refresh their tokens and a way of knowing if they are invalid or expired.

Typically, when a token is expired, the web application should try to refresh it and get the new one seamlessly in case a request to a protected resource fails. Having a function that refreshes the token given an access token should make it easy for people to do so.
The package calls the `/authorize` end point and receives **an access token**.

```json
{
"token_type":"Bearer",
"scope":"https://graph.microsoft.com/User.Read",
"expires_in":3600,
"ext_expires_in":3600,
"access_token":"xxxxxxx"
}
```

According to https://learn.microsoft.com/en-us/entra/identity-platform/v2-oauth2-auth-code-flow, we should be able to also return the refresh token.

> An OAuth 2.0 refresh token. The app can use this token to acquire other access tokens after the current access token expires. Refresh tokens are long-lived. They can maintain access to resources for extended periods. For more detail on refreshing an access token, refer to [Refresh the access token](https://learn.microsoft.com/en-us/entra/identity-platform/v2-oauth2-auth-code-flow#refresh-the-access-token) later in this article.
**Note: Only provided if offline_access scope was requested.**

The client user should have access to the refresh token, as well.