Changes user password(s) and/or access string.
See https://www.paws-r-sdk.com/docs/memorydb_update_user/ for full documentation.
memorydb_update_user(UserName, AuthenticationMode = NULL, AccessString = NULL)
[required] The name of the user
Denotes the user's authentication properties, such as whether it requires a password to authenticate.
Access permissions string used for this user.