This PR introduces custom types / substrate wrappers for `Multiaddr`,
`multiaddr::Protocol`, `Multihash`, `ed25519::*` and supplementary types
like errors and iterators.

This is needed to unblock `libp2p` upgrade PR
https://github.com/paritytech/polkadot-sdk/pull/1631 after
https://github.com/paritytech/polkadot-sdk/pull/2944 was merged.
`libp2p` and `litep2p` currently depend on different versions of
`multiaddr` crate, and introduction of this "common ground" types is
needed to support independent version upgrades of `multiaddr` and
dependent crates in `libp2p` & `litep2p`.

While being just convenient to not tie versions of `libp2p` & `litep2p`
dependencies together, it's currently not even possible to keep `libp2p`
& `litep2p` dependencies updated to the same versions as `multiaddr` in
`libp2p` depends on `libp2p-identity` that we can't include as a
dependency of `litep2p`, which has it's own `PeerId` type. In the
future, to keep things updated on `litep2p` side, we will likely need to
fork `multiaddr` and make it use `litep2p` `PeerId` as a payload of
`/p2p/...` protocol.

With these changes, common code in substrate uses these custom types,
and `litep2p` & `libp2p` backends use corresponding libraries types.