Ups changes for new release

Updating content for user guide to reflect the new developer role and user mgmt section.

Besides that, I had to update a lot of screenshots, due to UI changes on UPS and KC


Done for https://issues.jboss.org/browse/AGPUSH-1085
have merged the two paragraphs to one, feel fee to discard though:

"The difference between the admin and developer account types is that the former can access all PushApplications and Variants configured on the server, whereas the latter has access only to the PushApplications and Variants created by a user assigned to that account type.  Further, the administration of the UPS as well as management of it's user's in the **Keycloak Admin Console**, can only be performed with a user assigned to the admin account type."