added credentialsRefresher

[vkagamlyk]

Add the ability to Refresh Auth Token Credentials

Currently when credentials expire, driver will continue trying to connect with the outdated credentials. There is no ability to update or refresh login credentials (See neo4j#993).

This PR introduces the ability to pass an optional credentialsRefresher function to an authToken object which will change credentials as they become obsolete.

There are no breaking changes introduced in this PR.

There is a test which validates these modifications by using a simple credentialsRefresher not breaks serialization.

Also tested with AWS Neptune, new credentials were correctly used to create a new connection.

Intended use

async function createDriver() {
  let authToken = { scheme: "basic", realm: "realm", principal: "username", credentialsRefresher: signedHeader };

  return neo4j.driver(url, authToken, {
      encrypted: "ENCRYPTION_ON",
      trust: "TRUST_SYSTEM_CA_SIGNED_CERTIFICATES",
      maxConnectionPoolSize: 2,
      maxConnectionLifetime: 2000
    }
  );
}

[Cole-Greer]

Could you add a test which validates the refresher works and also demonstrates its use?

[Cole-Greer]

LGTM

[vkagamlyk]

opened as neo4j#1051