acl: remove Server.ResolveTokenIdentityAndDefaultMeta

This method suffered from similar naming to a couple other methods on Server, and had not great
re-use (2 callers). By copying a few of the lines into one of the callers we can move the
implementation into the second caller.

Once moved, we can see that ResolveTokenAndDefaultMeta is identical in both Client and Server, and
likely should be further refactored, possibly into ACLResolver.

This change is being made to make ACL resolution easier to trace.