Move and rename UserExtractionFilter -> UserCookieFilter and move to errai-security-server.

This filter is no-longer keycloak-specific. The .properties handling code has also been factored out into a producer mothod.
Move mock servlet classes to errai-security-server so they can be shared by other errai-security-* tests.
Only create one instance of Wrapped AuthenticationService in KeycloakAuthenticationService.