[Feature]: Pennyweights

### Describe the feature you want to add

Pennyweights (`dwt`) unit for `water`/`coffee`

### Describe your proposed solution

_No response_

### Describe alternatives you've considered, if relevant

_No response_

### Additional context

References:

1. https://www.metric-conversions.org/weight/grams-to-pennyweights.htm