* Add baseline benchmark for sr25519 verification

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

* Register keystore for correct test externalities

* Update frame/benchmarking/src/baseline.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* fix build

Co-authored-by: Parity Bot <admin@parity.io>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>