[storage-js] Return id of uploaded file

[bombillazo]

Hey, currently the storage API returns the ID of the file uploaded, but for some reason, the JS client only returns the file path.

I created a PR to remedy this and give parity to the JS client with the storage API:
supabase/storage-js#168

[bombillazo]

Hey, anyone on the Supabase team can take a look?