Companion for #13352 (#2180)

* Assets balances

* Update docs

* AssetsApi with MultiLocation as preparation for multi pallet_assets instances (#2187)

* AssetsApi with MultiLocation for Westmint + assets-common

* AssetsApi with MultiLocation for Statemine/t

* typo

* typo for check-docs job

* WIP: AssetsApi return MultiAsset instead of (MultiLocation, Balance)

* WIP: assets_api + conversion refactor

* WIP: assets_api + conversion refactor

* Finished asset runtimes

* Refactor AssetsApi to FungiblesApi

* Refactor

* Fix check-rust-docs

* Removed todo

* Fix check-rust-doc

* Update parachains/runtimes/assets/common/Cargo.toml

Co-authored-by: Bastian Köcher <git@kchr.de>

* update lockfile for {"substrate", "polkadot"}

---------

Co-authored-by: Branislav Kontur <bkontur@gmail.com>
Co-authored-by: parity-processbot <>
Co-authored-by: Bastian Köcher <git@kchr.de>

cumulus/parachains/runtimes/assets/common/Cargo.toml

@@ -0,0 +1,38 @@
+[package]
+name = "assets-common"
+version = "0.1.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2021"
+description = "Assets common utilities"
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "3.0.0", default-features = false, features = ["derive"] }
+
+# Substrate
+frame-support = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
+sp-api = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
+sp-std = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
+
+# Polkadot
+xcm = { git = "https://github.com/paritytech/polkadot", default-features = false, branch = "master" }
+xcm-builder = { git = "https://github.com/paritytech/polkadot", default-features = false, branch = "master" }
+xcm-executor = { git = "https://github.com/paritytech/polkadot", default-features = false, branch = "master" }
+
+# Cumulus
+parachains-common = { path = "../../../common", default-features = false }
+
+[build-dependencies]
+substrate-wasm-builder = { git = "https://github.com/paritytech/substrate", branch = "master" }
+
+[features]
+default = [ "std" ]
+std = [
+	"codec/std",
+	"frame-support/std",
+	"parachains-common/std",
+	"sp-api/std",
+	"sp-std/std",
+	"xcm/std",
+	"xcm-builder/std",
+	"xcm-executor/std",
+]