src: use per-realm GetBindingData() wherever applicable
src: add per-realm GetBindingData() method
This version avoids the additional access to the embedder slot when we already have a reference to the realm.
src: use per-realm GetBindingData() wherever applicable
This reduce the number of embedder slot accesses and also removes the assumption in a few binding methods that the current realm is the principal realm of the current environment (which is not true for shadow realms).