simplify client extension for working with not-quite-compliant servers

[hauntingEcho]

expand buildRequest and toScimException access from package-only to protected, and remove final modifier from builders. This allows easier wrapping for interaction with not-quite-compliant scim2 implementations

[samkeeleyong]

Is there any reason this hasn't been merged? I'm also having trouble integrating with not-quite-compliant servers so i needed to create my own "ScimService" that's partly copy pasted from the sdk.

[hauntingEcho]

@samkeeleyong AFAICT they haven't done the legal legwork to accept contributions (e.g. relicensing agreement), so they need to either do that or rewrite similar changes themselves:

Ping Identity does not accept third-party code submissions, such as pull requests.: https://github.com/pingidentity/scim2/blob/master/CONTRIBUTING.md

I'm happy to license this PR globally under the WTFPLv2 with no-warranty clause, which should be fine for your needs and whatever form Ping will eventually want:

This PR is free software. It comes without any warranty, to
the extent permitted by applicable law. You can redistribute it
and/or modify it under the terms of the Do What The Fuck You Want
To Public License, Version 2, as published by Sam Hocevar. See
http://www.wtfpl.net/ for more details.