Benchmarks

[Claudson Oliveira]

The idea of this issue is exactly what we had on #23, I'm duplicating it as an upvote with the hope that we are getting some contribution on hacktoberfest21.

What we expect is to see some numbers on how gitql behaves with big repositories such as kubernetes. Does the queries with filtering take longer to respond?
Some ideas on how this could be achieved:

• Use the go testing package to create some benchmarks from the source code point of view ( against the function runtime.runQuery() )
• Any other benchmark tool (pure bash script is also accepted)
• Run the benchmark on every merge on GitHub Actions, if possible mark the job as allow_failure.