[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/chains/relays/westend/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "westend-emulated-chain"
+version = "0.0.0"
+authors.workspace = true
+edition.workspace = true
+license = "Apache-2.0"
+description = "Westend emulated chain"
+publish = false
+
+[dependencies]
+serde_json = "1.0.104"
+
+# Substrate
+sp-core = { path = "../../../../../../../substrate/primitives/core", default-features = false }
+sp-runtime = { path = "../../../../../../../substrate/primitives/runtime", default-features = false }
+sp-authority-discovery = { path = "../../../../../../../substrate/primitives/authority-discovery", default-features = false }
+sp-consensus-babe = { path = "../../../../../../../substrate/primitives/consensus/babe", default-features = false }
+beefy-primitives = { package = "sp-consensus-beefy", path = "../../../../../../../substrate/primitives/consensus/beefy" }
+grandpa = { package = "sc-consensus-grandpa", path = "../../../../../../../substrate/client/consensus/grandpa", default-features = false }
+pallet-im-online = { path = "../../../../../../../substrate/frame/im-online", default-features = false }
+pallet-staking = { path = "../../../../../../../substrate/frame/staking", default-features = false }
+
+# Polkadot
+polkadot-primitives = { path = "../../../../../../../polkadot/primitives", default-features = false }
+westend-runtime-constants = { path = "../../../../../../../polkadot/runtime/westend/constants", default-features = false }
+westend-runtime = { path = "../../../../../../../polkadot/runtime/westend" }
+
+# Cumulus
+parachains-common = { path = "../../../../../../parachains/common" }
+emulated-integration-tests-common = { path = "../../../common", default-features = false }