Pioneer upgrade: Upgrading EntityCodec-related functionality (joy-media)

[Lezek123]

This is mostly related to upgrading and re-enabling the joy-media app, but I decided to split this process into two separate issues, as joy-media itself relies on a particular mechanism of encoding and decoding entities to/from Codec types, which I suspect is going to be heavily affected by the polkadot-js upgrade (forcing us to handle the creation of Codec type in a quite different way than before). Succesfully adjusting this mechanism to work with the new polkadot-js will be a great milestone in upgrading the media app.

[Lezek123]

Closing, as this is already partially covered by the @joystream/types upgrade (#1124) and further adjustments will be probably strictly inside joy-media, so I'm going to cover this in #1048