Adding benchmarking for new `frame_election_provider_support` (#11149)

* First stab at adding benchmarking for
`election-provider-support` onchain

* Adding `BoundedPhragMMS` and fixing stuff

* Fixing node runtime

* Fixing tests

* Finalising all benchmarking stuff

* better comments

* Better benchmarking config

* Better `WeightInfo` and benchmarking

* Fixing tests

* Adding some documentation

* Fixing some typos

* Incorporating review feedback

* cleanup of rustdocs

* rustdoc changes

* changes after code review

* Fixing some errors.

* Fixing dependencies post merge

* Bringing back `UnboundedExecution`

* Better rustdoc and naming

* Cargo.toml formatting