Create mapping or function that wraps at a configurable `textwidth`

[ZeroKnight]

The idea is that this would be mostly for comments and docstrings, but might have other uses.

Notes

Setting width:

• Supplying [count] gives an explicit width
• Buffer-local width via b:aux_textwidth
• Global width via g:aux_textwidth

Map to something like gQ<motion>

[ZeroKnight]

Alternatively, leave textwidth to handle prose and instead enforce line lengths with formatters.