Add benchmarks

[amirouche]

Have a way to run benchmarks:

• use linux perf-tools to gather statistics
• benchmark compilation separatly
• aggregation for:
  • memory use
  • wall-clock time
• benchmark safe and unsafe
• score board
• add a github actions that can only be run via the interface (ie. no triggers)

ref: https://github.com/benchmark-action/github-action-benchmark
ref: ecraven/r7rs-benchmarks#60
ref: ecraven/r7rs-coverage#4
ref: https://github.com/larcenists/larceny/tree/master/test/Benchmarking/R6RS/src
ref: https://benchmarksgame-team.pages.debian.net/benchmarksgame/index.html
ref: https://github.com/gothinkster/realworld
ref: https://www.techempower.com/benchmarks/

[amirouche]

re github-action-benchmark is not what is needed. We would need something that can compare several implementations, and then aggregate the results of various metrics, and eventually get together a scoreboard.