[xcm-emulator] Chains generic over Network & Integration tests restructure (#2092)

Closes:
- #1383 
- Declared chains can be now be imported and reused in a different
crate.
- Chain declaration are now generic over a generic type `N` (the
Network)
- #1389
- Solved #1383, chains and networks declarations can be restructure to
avoid having to compile all chains when running integrations tests where
are not needed.
- Chains are now declared on its own crate (removed from
`integration-tests-common`)
- Networks are now declared on its own crate (removed from
`integration-tests-common`)
    - Integration tests will import only the relevant Network crate
- `integration-tests-common` is renamed to
`emulated-integration-tests-common`

All this is necessary to be able to implement what is described here:
https://github.com/paritytech/roadmap/issues/56#issuecomment-1777010553

---------

Co-authored-by: command-bot <>

cumulus/parachains/integration-tests/emulated/networks/westend-system/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "westend-system-emulated-network"
+version = "0.0.0"
+authors.workspace = true
+edition.workspace = true
+license = "Apache-2.0"
+description = "Westend System emulated network"
+publish = false
+
+[dependencies]
+# Cumulus
+emulated-integration-tests-common = { path = "../../common", default-features = false }
+westend-emulated-chain = { path = "../../chains/relays/westend", default-features = false }
+asset-hub-westend-emulated-chain = { path = "../../chains/parachains/assets/asset-hub-westend" }
+bridge-hub-westend-emulated-chain = { path = "../../chains/parachains/bridges/bridge-hub-westend" }
+penpal-emulated-chain = { path = "../../chains/parachains/testing/penpal" }