feat: add bench method & update example

[jhen0409]

add a benchmark method.

other updates:

• Bump RN version from 0.73 to 0.74 in example (our internal projects still using RN 0.74)
• Add Bench container in example

TODO:

• add bench method
• add bench example

[sooryranga]

@jhen0409 is it possible to get a release for this change? Thank you.

[jhen0409]

@jhen0409 is it possible to get a release for this change? Thank you.

I'll make a release after #267. Also, I found some possible memory leak issue of whisper.cpp and needs to be checked, so it may be still a beta version.