Benchmark for char expression

[ajita-asthana]

Which issue does this PR close?

• Related [datafusion-spark] Optimize char expression #16009

Rationale for this change

Add a benchmark to measure char performance, can be reviewed once the char.rs implementation is merged.

What changes are included in this PR?

adds a new file in benches directory.

Are these changes tested?

Are there any user-facing changes?

Nil

[comphead]

Thanks @ajita-asthana for your first contribution
I think it would be great having a bench for char function.

[comphead]

I changed PR header to related instead of closed as the #16009 expects both bench and optimization implementation which I believe is another your PR #16076

[ajita-asthana]

Thanks @comphead I will fix the linux build failure.

[ajita-asthana]

char             
                        time:   [18.805 µs 19.026 µs 19.274 µs]
                        change: [+339.25% +341.54% +344.44%] (p = 0.00 < 0.05)

[crepererum]

thanks