* split implementation in multiple files:
* transformation -> genesis_config/ getters.rs instance_trait.rs metadata.rs mod.rs store_trait.rs
* mod.rs -> parser.rs
* impl.rs -> storage_struct.rs
* parser is isolated into parse module, it could be improved as well but this can be done in another PR
* modules contains a defintion of decl_storage input which must be ok to work with.
* implementation change:
* T: Trait might be more often bound to 'static (anyway we only use static one and it is needed for metadata current implementation).
* GenesisConfig no longer requires its fields to be Clone (possible since to EncodeLike feature)
* builder for map storages must return precise type Vec<(key, value)>