Add Native Sharing REST API (#1150)

* Initial draft - UNTESTED

* changes to Save() and Update()

* apply col filter and limit nanoid

* remove columns to not update

core/wire_providers.go

@@ -16,4 +16,5 @@ var Set = wire.NewSet(
 	NewCacheWarmer,
 	NewPlayers,
 	transcoder.New,
+	NewShare,
 )