feat: short with value in same arg

[shadowspawn]

(This PR builds on #68 so the diff is currently noisy. To see the new code in the meantime look for isShortAndValue.)

Add support for combining an option and its value in the same argument. For example these are the same using the tail command:

tail -n 3 index.js 
tail -n3 index.js 

Or with parseArgs:

parseArgs(['-n', '3'], { withValue: ['n'] });
parseArgs(['-n3'], { withValue: ['n'] });

NB: this is the classic pattern with value directly following short and not the same pattern included in #62 which used -n=3. Which might prompt some discussion...

[shadowspawn]

Working on redo of this with new configuration bag of options.

[shadowspawn]

Redid work in #75 after #63 landed.