Split up BindingDOMRpcImplementationAdapter

We create an instance of this class for each RPC registration, which means we need to dynamically create a SchemaPath on each invocation.

That schema path is used for lookup in the codec tree cache, which is lazily instantiated. Since we are using a different SchemaPath object on each lookup, equals() part of the cache lookup strays away from the identity comparison, leading to lost performance.

Break up the Adapter such that we maintain a per-method registration, which retains the registration SchemaPath. This will result in the lookup not allocating any objects and keeping on the identity path.