[Woo POS] Add an option to toggle Cha-Ching sound

[AnirudhBhat]

The goal of this task is to provide users an ability to enable/disable Cha-Ching sound on successful payment in POS. Having this customisation ability would enable users who don't want or find the sound repetitive during the peak hours can turn off when not required.

[dangermattic]

Thanks for reporting! 👍