Whitelist Transactional key (#11394)

* Make constants public

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Whitelist the transactional layer

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* 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

Co-authored-by: Parity Bot <admin@parity.io>