Benchmark Treasury Pallet (#5287)

* Start benchmarks

* try_origin or root

* More benches

* stuck

* Custom trait functions for benchmarks

* finish benchmarks

* Bump impl

* More comments

* Bump spec

* Remove import

* Update frame/elections-phragmen/src/lib.rs

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* Update frame/support/src/traits.rs

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* Fix merge

Co-authored-by: thiolliere <gui.thiolliere@gmail.com>