ADR 019 password rotation

[StephenCathcart]

This PR updates the preview feature "re-auth" significantly. The changes allow for catering to a wider range of use cases including simple password rotation.

ExpirationBasedTokenManager was renamed to BearerTokenManager for handling potentially expiring auth information:

func ExampleBearerTokenManager() {
    fetchAuthTokenFromMyProvider := func(ctx context.Context) (neo4j.AuthToken, *time.Time, error) {
        // some way of getting a token
        token, err := getSsoToken(ctx)
        if err != nil {
            return neo4j.AuthToken{}, nil, err
        }
        // assume we know our tokens expire every 60 seconds
        expiresIn := time.Now().Add(60 * time.Second)
        // Include a little buffer so that we fetch a new token *before* the old one expires
        expiresIn = expiresIn.Add(-10 * time.Second)
        // or return nil instead of `&expiresIn` if we don't expect it to expire
        return token, &expiresIn, nil
    }
    // create a new driver with a bearer token manager which uses provider to handle possibly expiring auth tokens.
    _, _ = neo4j.NewDriverWithContext(getUrl(), auth.BearerTokenManager(fetchAuthTokenFromMyProvider))
}

A BasicTokenManager token manager was added to handle password rotation:

func ExampleBasicTokenManager() {
    fetchBasicAuthToken := func(ctx context.Context) (neo4j.AuthToken, error) {
        // some way of getting basic authentication information
        username, password, realm, err := getBasicAuth()
        if err != nil {
            return neo4j.AuthToken{}, err
        }
        // create and return a basic authentication token with provided username, password and realm
        return neo4j.BasicAuth(username, password, realm), nil
    }
    // create a new driver with a basic token manager which uses provider to handle basic auth password rotation.
    _, _ = neo4j.NewDriverWithContext(getUrl(), auth.BasicTokenManager(fetchBasicAuthToken))
}

[StephenCathcart]

[Go] Re-authentication on credentials changing/password rotation