Consolidate SM SAML and make SAML docs more consistent

Problem to solve

1. Overlap between SAML for self-managed (SM) and Group SAML (for SaaS), which may be duplicated
2. Different "policies" for the two products.
   • SaaS specifically says we don't "fully" support what is not listed
   • SM has nothing like that, and we have a couple of different documented which are not the same as SaaS.
3. Because SM has separate pages by provider, a lot of information is duplicated.

Side note, this came up during a Slack discussion (internal) where I promised to start an issue to discuss.

Proposal

1. Take a larger look at our SAML docs for both SM and SaaS.
2. Consolidate the couple of SM SAML docs so that we have one "how to configure" section with notes on specific providers in sections, similar to Group SAML page. The provider specific pages look to be a mix of SAML, OmniAuth, and OAuth.
3. Ensure there's no duplication of content.
4. Move 3rd party screenshots if there are any to troubleshooting page.

Who can address the issue

1. If we can get TW agreement, then Support can get this work done.