Add benchmark for gRPC GetValidatorSet

[hexfusion]

Why this should be merged

It is important to understand the cost of requesting a large validator set over gRPC. Even though the call is local there is a cost for round trip serialization. The server + wire cost for serving 2000 records is only about 1.6ms. The rest of the time is spent converting bytes to BLS keys (cgo) client side.

ref

avalanchego/snow/validators/gvalidators/validator_state_client.go

Line 75 in 7d73b59

publicKey, err = bls.PublicKeyFromBytes(validator.PublicKey)

$ go test -benchmem -run=^$ -bench ^BenchmarkGetValidatorSet$ github.com/ava-labs/avalanchego/snow/validators/gvalidators -memprofile benchvset.mem -cpuprofile benchvset.cpu

goos: linux
goarch: amd64
pkg: github.com/ava-labs/avalanchego/snow/validators/gvalidators
cpu: Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz
BenchmarkGetValidatorSet/get_validator_set_1_validators-12                 12841            106797 ns/op            9913 B/op        194 allocs/op
BenchmarkGetValidatorSet/get_validator_set_10_validators-12                 1710            670164 ns/op           16391 B/op        266 allocs/op
BenchmarkGetValidatorSet/get_validator_set_500_validators-12                  37          28670401 ns/op          386569 B/op       3744 allocs/op
BenchmarkGetValidatorSet/get_validator_set_1000_validators-12                 19          56178525 ns/op          763855 B/op       7269 allocs/op
BenchmarkGetValidatorSet/get_validator_set_2000_validators-12                  9         111610799 ns/op         1503906 B/op      14323 allocs/op

profiles

benchvset.cpu
benchvset.mem

How this works

Uses golang native benchmark tooling

How this was tested

manual

[StephenButtolph]

nits