Provide a way to get entity type from UUri

[evshary]

Just as we discussed here eclipse-uprotocol/up-transport-zenoh-rust#93 (comment), it would be convenient if we could provide a function for transport layers to get the entity type from UUri.

[sophokles73]

Can you elaborate a little regarding what you would expect to get, e.g. by means of an example?

[evshary]

Can you elaborate a little regarding what you would expect to get, e.g. by means of an example?

Perhaps something like uri.get_entity_type(), which will return u16.
For example if ue_id in uri is 0x12345678, it will return 0x5678.