SAML Users should be able to be deleted using the UI

Currently we cannot delete SAML users, the button appears inactive on the User administration panel, normally external users are not deleted, but with saml users being stored in a cache ( database table), there is a need to delete them from that cache.

AC

• The button on the UI of user administration for deleting is active
• Saml Users are correctly deleted from Nexus Repo SAML user cache after hitting the button, and confirmation, (user and user role mappings, any associated API tokens, related to that specific user in the SAML realm should be gone)