Use sp-metadata-ir from substrate to work with metadata

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

metadata/Cargo.toml

@@ -18,6 +18,7 @@ codec = { package = "parity-scale-codec", version = "3.0.0", default-features =
 frame-metadata = { version = "15.1.0", features = ["v14", "v15-unstable", "std"] }
 scale-info = "2.5.0"
 sp-core-hashing = "7.0.0"
+sp-metadata-ir = { git = "https://github.com/paritytech/substrate.git", version = "0.1.0" }
 
 [dev-dependencies]
 bitvec = { version = "1.0.0", default-features = false, features = ["alloc"] }

metadata/src/lib.rs

@@ -5,6 +5,8 @@
 mod retain;
 mod validation;
 
+pub use sp_metadata_ir as metadata_ir;
+
 pub use retain::retain_metadata_pallets;
 pub use validation::{
     get_call_hash, get_constant_hash, get_metadata_hash, get_metadata_per_pallet_hash,