Companion for #13287 (#2155)

* parachains: Adjust `sp_api::Metadata` to the new API

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* parachains: Implement new Metadata trait for bridge/polkadot

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* update lockfile for {"substrate", "polkadot"}

---------

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>
Co-authored-by: parity-processbot <>