Token-swap-over-bridge pallet (#944)

* token swap pallet

* token swap type (replay protection)

* post-merge fixes

* post-merge fix

* Update modules/token-swap/src/lib.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* Update modules/token-swap/src/lib.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* add missing comment part

* Update modules/token-swap/src/lib.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* starting claim after lock period is over is forbidden

* move spec_version and weight to arguments

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

bridges/primitives/token-swap/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "bp-token-swap"
+description = "Primitives of the pallet-bridge-token-swap pallet"
+version = "0.1.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "2.0.0", default-features = false }
+
+# Substrate Dependencies
+
+frame-support = { git = "https://github.com/paritytech/substrate", branch = "master" , default-features = false }
+sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" , default-features = false }
+
+[features]
+default = ["std"]
+std = [
+	"codec/std",
+	"frame-support/std",
+	"sp-core/std",
+]