(XP 4.0.z) Add newly added constants for bearer-only support to org.wildfly.security.http.oidc.Oidc

ELY-2362 added support for the bearer-only option when using the OIDC mechanism. As part of these changes, new constants were added in the org.wildfly.security.http.HttpConstants class which is part of the org.wildfly.security:wildfly-elytron-http artifact.

This is problematic for XP4 where only the org.wildfly.security:wildfly-elytron-http-oidc dependency is present in the main pom.xml file. In order to update to a org.wildfly.security:wildfly-elytron-http-oidc version that contains the new bearer-only support, the version of org.wildfly.security:wildfly-elytron-http would also need to be updated but that comes in via Core.

To work around this problem, we can add the new constants to org.wildfly.security.http.oidc.Oidc. Note that HttpConstants is public API so we can't remove the constants from there but can determine if those should be deprecated or not.