Make E-Mail address mandatory

Identities with no e-mail address attached must add an address, else they can not use any service.

Entrypoints for Dev: bwreg-webapp: /user/email-addresses.xhtml Entrypoint for Access: bwreg-webapp: edu.kit.scc.webreg.sec.SecurityFilter around Line 215

Done when: Identity must have a primary e-mail address, else no actions are possible.