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