Improve performance benchmarks coverage after migration to ASV

[tanujkhattar]

Currently, the performance benchmarks in Cirq are very limited. We should improve the coverage of performance benchmarks by adding more tests.

We should discuss

• Which functions / code pieces are worth benchmarking?
• Should we have benchmarks for all functions / modules ?

Decide a strategy and then implement the additional benchmarks using ASV.

Related: #3822 #1124

[95-martin-orion]

Discussed in Cirq sync:

• We need to incorporate benchmarks into the PR review workflow (specifically highlighting regressions, not blocking PRs)
• General concern around hard-to-detect gradual slowdown of code

@tanujkhattar Do we have this kind of support, or designs around it?