SSO/SAML support

Hi dear stackstorm maintainers/community!

I've been working on a PR to implement SSO/SAML using whatever we currently have as a base (st2-auth-backend-sso-saml2) and some other bits and pieces of SSO through the main st2 repository.

I asked around in slack if this had any traction and apparently not, so I just went ahead and started implementing some of it because we need that for our strategy at the company I work for.

Are there any other guidelines regarding contribution other than these items? https://github.com/StackStorm/st2/blob/abb694b85f75dc543ecea7df6b87def4bce53309/CONTRIBUTING.rst https://docs.stackstorm.com/development/index.html

I am currently focusing on getting it working on manual tests and will write proper tests afterwards, but can I count on some assistance to further validate/refine this as it progresses?

here's a bit of how it looks so far.. https://user-images.githubusercontent.com/1406885/164324464-29150514-1b5c-415d-bb71-d1e5f2cf568a.mp4

if you have any SAML/SSO material, that would be lovely as well.. currently I've been trying to base the implementation off gravitational/teleport

thanks!!