test-runtime: json_patch dep removed (#3062)

We don't need dependency on `json_patch` there is implementation of
needed function in `sc_chain_spec` crate.
This PR makes this function publicly available and removes the dep.

substrate/client/chain-spec/src/lib.rs

@@ -338,6 +338,7 @@ pub use self::{
 		GenesisBlockBuilder,
 	},
 	genesis_config_builder::GenesisConfigBuilderRuntimeCaller,
+	json_patch::merge as json_merge,
 };
 pub use sc_chain_spec_derive::{ChainSpecExtension, ChainSpecGroup};