Try-state for Referenda pallet (#13949)

* Try-state for Referenda pallet

* fix & more tests

* checking more stuff

* remove log

* two more tests

* Update frame/referenda/src/lib.rs

Co-authored-by: Muharem Ismailov <ismailov.m.h@gmail.com>

* fixes

* new check

* merge fixes

* fix warning

* remove check

* Update frame/referenda/src/lib.rs

Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>

* separate into multiple functions

* clean up

* unnecessary return value specified

* fix

* Update frame/referenda/src/lib.rs

* fmt

* remove import

* fmt

* fix CI

* Update frame/referenda/src/lib.rs

Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>

* last fixes

* :P

* fmt

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Co-authored-by: Muharem Ismailov <ismailov.m.h@gmail.com>
Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>
Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>