Move AuthenticatedRegistrarAccessor to request/auth/

It is starting to be used in more places than just ur/server/registrar. Even now it's used in the RDAP, and we are going to start using it for the registrar-xhr endpoint meaning it will be used in EPP flows as well.

Also logically - this is part of the request authentication.

While moving - we also refactor it to make it easier to use in tests. Instead of mocking, we will be able to create instances with arbitrary roles.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221645055

java/google/registry/request/HttpException.java

@@ -115,6 +115,10 @@ public abstract class HttpException extends RuntimeException {
       super(HttpServletResponse.SC_FORBIDDEN, message, null);
     }
 
+    public ForbiddenException(String message, Exception cause) {
+      super(HttpServletResponse.SC_FORBIDDEN, message, cause);
+    }
+
     @Override
     public String getResponseCodeString() {
       return "Forbidden";