* SAML: single logout WIP

* SAML: sign SAML requests

* SAML: remove unnecessary logs

* fix go mod file

* Docs: Single Logout

* SAML: use api endpoint for single logout

* Apply suggestions from code review

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

* SAML: save context for single logout

* Chore: add SAML dependencies

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>