Merge xmr_btc crate

Created network, storage and protocol modules. Organised
files into the modules where the belong.

xmr_btc crate moved into isolated modulein swap crate.

Remove the xmr_btc module and integrate into swap crate.

Consolidate message related code

Reorganise imports

Remove unused parent Message enum

Remove unused parent State enum

Remove unused dependencies from Cargo.toml

.github/workflows/ci.yml

@@ -34,7 +34,6 @@ jobs:
       - name: Check Cargo.toml formatting
         run: |
           cargo tomlfmt -d -p Cargo.toml
-          cargo tomlfmt -d -p xmr-btc/Cargo.toml
           cargo tomlfmt -d -p monero-harness/Cargo.toml
           cargo tomlfmt -d -p swap/Cargo.toml