storage: Fix partial key storage iteration

[lexnv]

This PR fixes the partial key storage iteration.

The storage key constructed by partial inputs was converted to the root storage key entry.
This meant that any partial input parameters provided to the key were completely ignored; and resulted in a wrongful behavior of iterating over all storage entries, rather than just the ones starting with the partial key.

To mitigate this behavior, the address bytes take into account the provided parameter inputs.
This loosens the expectations of utils::storage_address_bytes, which now only returns errors if the provided input types exceed the number of types from the metadata. Before this PR, the function expected an identical match in terms of the number of inputs.

Testing Done

• Manual testing with the metadata from "wss://rpc.relay.blockchain.enjin.io:443"
• Added an unit test that creates two assets, and checks that partial iterations result in the expected number of items

Closes: #1251

[tadeohepperle]

Ah nice, great work! :)