Multiple helpers (AWS) and static variables are missing from the Scala MongoCredential wrapper.

See: https://mongodb.github.io/mongo-java-driver/5.1/apidocs/mongo-scala-driver/org/mongodb/scala/MongoCredential$.html

Acceptance criteria

• Add all missing methods/constants
• Regression test to assert that any new ones methods/constants added to the Java API are also added to Scala. This can be done by comparing the APIs using reflection
• Check if this effects any other APIs besides MongoCredential