perf: add Krausest inspired tests as default test suite

[prudepixie]

This would be an important addition, as I'm adding tests to FAST libraries, there are a lot of repeated code that could be condensed. Most of the tests are run by creating # items and run # times through tachometer (with different implementation for benchmarking).
But essentially, we'd be interested in collecting similar data- where we define performance.mark and performance.measure- including start up metrics, CPU, memory (as Krausest framework).
Thus, it would benefit from having some templates that does this.

[prudepixie]

As I progressed in this ticket, I realized on top of having a default set of tests or operations to run for a benchmark, there should probably be an option to allow users to write their own 'operation' to test their benchmark. So in conjuncture with this work, I wanted to restructure the layout to make this possible.