fix: Add warning when password is set without username

[adam-abdelrahman0]

Ref #1685

This change implements a warning if a password is provided without a username in an IClientOptions object in the connect() function.

• index.ts: add condition after parseAuthOptions() to warn if no username has been set.

[robertsLando]

@adam-abdelrahman0 there is no specification that explains this, I mean someone could have users with empty username for whatever reason, cannot accept this PR