De-dupe duplicated primitives structs from pallas-network (by switching to generics)

[scarmuega]

To avoid an unnecessary coupling between pallas-network -> pallas-primitives, we opted for duplicating ledger-related structs required for some of the mini-protocols in pallas-network. This is tech-debt that we need to deal with before committing to a v1.

DoD:

• generalize (aka: add a generic type param) to mini-protocols that require ledger-specific structs: LocalStateQueries and LocalTxSubmit.
• move all ledger-specific structs that currently reside in pallas-network to pallas-primitives and unify duplicates.
• adjust example code to show how to interact with mini-protocols that require ledger structs.