Pallet: Atomic Swap (#6349)

* Init atomic swap pallet

* Implement module swap operations

* Add successful swap test

* Bump node spec_version

* Fix storage name

* Add ProofLimit parameter to prevent proof size being too large

* Add missing events

* Basic weight support

* Add basic docs

* Mark swap on claim

This handles the additional case if `repatriate_reserved` fails.

* Add additional expire handler

* Update frame/atomic-swap/src/lib.rs

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

* Add docs on ProofLimit

* Fix test

* Return Ok(()) even when the transfer fails

Because we need to mark the swap as claimed no matter what.

* Remove retry logic

It's overkill. Swap is about something being executed, not necessarily successful.
Although there should be logic (reserve and unreserve) to make it so that both parties *believes*
that the execution is successful.

* succeed -> succeeded

* Add docs on duration -- revealer should use duration shorter than counterparty

* Missing trait type

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

substrate/Cargo.lock

@@ -3845,6 +3845,21 @@ dependencies = [
  "sp-std",
 ]
 
+[[package]]
+name = "pallet-atomic-swap"
+version = "2.0.0-rc3"
+dependencies = [
+ "frame-support",
+ "frame-system",
+ "pallet-balances",
+ "parity-scale-codec",
+ "serde",
+ "sp-core",
+ "sp-io",
+ "sp-runtime",
+ "sp-std",
+]
+
 [[package]]
 name = "pallet-aura"
 version = "2.0.0-rc3"