Feature-gate the parachain-related code #485
Description
When referencing the StorageHub runtime & client code, some cumulus / parachain -related dependencies are being pulled in that leads to the compilation of a cumulus-relay-chain-minimal-node, which overall greatly impact compilation times. This dependency chain comes mostly from the HostFunctions type in the shc-common crate.
It would be best to feature-gate all cumulus / parachain -related code with a parachain feature, so that chains that want to integrate StorageHub features as part of a solochain implementation do not pull unnecessary dependencies and don't see their compilation time impacted.