Non-Interactive Staking (#12610)

* Improve naming.

* More improvements to naming

* Fungible counterpart

* Shared pot instead of reserve

* Transferable receipts

* Better naming

* Use u128 for counterpart

* Partial thawing

* Docs

* Remove AdminOrigin

* Integrate into Kitchen Sink

* Thaw throttling

* Remove todo

* Docs

* Fix benchmarks

* Building

* Tests work

* New benchmarks

* Benchmarking tests

* Test new defensive_saturating_* functions

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* fmt

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Formatting

* Update frame/nis/src/lib.rs

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Apply suggestions from code review

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Events added

* Fix kitchensink

* Update frame/nis/src/lib.rs

Co-authored-by: Xiliang Chen <xlchen1291@gmail.com>

* Review niggles

* Remove genesis build requirements

* Grumbles

* Fixes

* Fixes

* Fixes

* Update frame/nis/src/lib.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update primitives/runtime/src/traits.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Formatting

* Fixes

* Fix node genesis config

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Fix node chain specs

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Use free asset ID as counterpart

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Account for rounding errors in fund_deficit bench

Relaxes the check for the NIS account balance in the fund_deficit bench
from equality from to checking for 99.999% equality. The exact deviation
for the kitchensink runtime config is 1.24e-10 percent but could vary if
the config is changed.

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* clippy

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* fmt

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Fix

* Rename

* Fixes

* Fixes

* Formatting

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Xiliang Chen <xlchen1291@gmail.com>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

substrate/primitives/runtime/src/traits.rs

@@ -515,6 +515,11 @@ impl<T> Convert<T, T> for Identity {
 		a
 	}
 }
+impl<T> ConvertBack<T, T> for Identity {
+	fn convert_back(a: T) -> T {
+		a
+	}
+}
 
 /// A structure that performs standard conversion using the standard Rust conversion traits.
 pub struct ConvertInto;
@@ -524,6 +529,12 @@ impl<A, B: From<A>> Convert<A, B> for ConvertInto {
 	}
 }
 
+/// Extensible conversion trait. Generic over both source and destination types.
+pub trait ConvertBack<A, B>: Convert<A, B> {
+	/// Make conversion back.
+	fn convert_back(b: B) -> A;
+}
+
 /// Convenience type to work around the highly unergonomic syntax needed
 /// to invoke the functions of overloaded generic traits, in this case
 /// `TryFrom` and `TryInto`.