hooks: enforce version on hook emission

Pass the minimum required version to the hook emission and only call
events when the handler is recent enough.
Add some macros to make event emission easier to read.

src/modules/module-protocol-native/connection.h

@@ -29,6 +29,8 @@ extern "C" {
 
 struct pw_protocol_native_connection_events {
 #define PW_VERSION_PROTOCOL_NATIVE_CONNECTION_EVENTS	0
+	uint32_t version;
+
 	void (*destroy) (void *data);
 
 	void (*error) (void *data, int error);