[ELY-201] Add client side HTTP authentication mechanism support

[keshav-redhat]

https://issues.redhat.com/browse/ELY-201

[Skyllarr]

@keshav-redhat Just a minor, if you'll have time, you can consider and add to this proposal the ideas you had about how to make this extensible for other clients than java HTTP client, like apache HTTP client for example. Thank you!