Auth methods section update

[selmaVH1]

fixes #8671 ; fixes #6988; fixes #7264 The goal of this PR is to update the Authentication Methods section. In addition to addressing the referenced tickets, I have also:

• Added AWSS3 authentication
• Removed Stored Identity authentication configs
• Added Identity-cert authentication

Feedback is welcome, especially regarding the descriptions of each method.

I removed Planetary auth method so backport can be done..

[DelazJ]

@selmaVH1 lgtm. But if you want the PR to be back ported automatically you need to rebase the branch before we merged, because of the "merge branch master" commit. Or it will fail and have to be done manually.