Run benchmarks on CI

We should run benchmarks on CI (using our self-hosted GitHub Actions runner?), parse results with https://golang.org/x/tools/benchmark/parse or https://golang.org/x/perf/benchfmt, convert them to JSON/BSON, and push to FerretDB to visualize in Grafana.

We already do something similar in dance: https://github.com/FerretDB/dance/blob/main/internal/pusher/pusher.go