Added benchmarks for class case.
Added benchmarks for class case.

This one is really alarming.

Benchmark results:

```
test cases::classcase::tests::bench_class_case             ... bench: 161,729,165 ns/iter (+/- 5,749,916)
test cases::classcase::tests::bench_class_from_snake       ... bench: 161,050,766 ns/iter (+/- 3,355,236)
test cases::classcase::tests::bench_is_class               ... bench: 162,549,957 ns/iter (+/- 41,483,599)
```

whatisinternet/Inflector