fix a few more things with nomination pools (#11373)

* fix a few more things with nomination pools

* add bench

* use weight fn

* cargo run --quiet --profile=production  --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark pallet --chain=dev --steps=50 --repeat=20 --pallet=pallet_nomination_pools --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/nomination-pools/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* allow real root to also set roles

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

Co-authored-by: Oliver Tale-Yazdi <[email protected]>

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

Co-authored-by: Oliver Tale-Yazdi <[email protected]>

* move out of the closure

* fix a few more things

Co-authored-by: Parity Bot <[email protected]>
Co-authored-by: Oliver Tale-Yazdi <[email protected]>