Fuzz testing for nomination pools (#12002)

* some additional tests and stuff

* make sanity public

* add some sort of fuzz test for pools

* breaks every now and then

* breaks every now and then

* IT WORKS AND PASSES 100k TESTS

* cleanup

* safe id addition

* fix assert_eq_error_rate

* Update frame/nomination-pools/src/tests.rs

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

* Update frame/nomination-pools/src/tests.rs

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

* add some doc

* Fix

* ".git/.scripts/fmt.sh" 1

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