Performance regression checks: benchmarking tests

[lcauser-oqc]

Performance regression checks when merging to main.

This first PR adds a number of performance benchmarks that will enable us to ensure that we do not introduce performance regressions to QAT.

• Added pytest-benchmark to allow us to run performance benchmarks.
• Introduced a variety of benchmarks in the form of QASM files that will test compilation performance (let me know if there are any more you would like to see...).
• Updated README to explain how the benchmarks can be used.

The workflow to automatically compare performance to main follows in #235.

Note: There are some temporary benchmark tests that are only there for demonstration purposes, and will be removed before merging.

[keriksson-rosenqvist]

LGTM