Change `ActiveDirectoryLdapAuthenticationProvider` to use `LdapClient`

[jzheaux]

[dineshgupta630]

@jzheaux
I would love the opportunity to contribute to this issue, if it's still available. Please do let me know.
Thank you so much!

[jzheaux]

Thanks, @dineshgupta630, for volunteering! I've assigned the issue to you.