Clean Phragmén Equlise API (#5452)

* Clean phragmen API and equalise()

* Stabilize new api

* Fix phragmen fuzzers

* More fixes

* Make fuzzers reproducible

* improvements

* Make equalize update assignments as well.

* total function for staked_assignment.

* Fix fuzzer build

* remvoe TODO

* Fix a bunch more.

* clean stray debug stuff

* Update primitives/phragmen/src/lib.rs

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

* fix range function

* fix number generator

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