core refactor

[tzemanovic]

There are couple left over things in  namada_core::ledger mod that can be moved out:

• eth (only addresses that can go in core/src/types/address.rs or ethereum_bridge crate)
• inflation can probably go into token crate - #2484
• replay protection is spread out - it could maybe be its own crate
• Flatten the core types  module so that we're just importing e.g. namada_core::dec  etc.

Also check and remove any unused deps.