fix: parsing hints should apply for dot notation keys

[bcoe]

No description provided.

[bcoe]

@JeroenVdb this feature is now ready to be released, I would love your help testing:

npm i yargs@next --save

[JeroenVdb]

@bcoe using the new Yargs version has indeed the expected result!

node yargs-example.js --metric.list AA --metric.list BB --metricList CC --metricList DD
{ _: [],
  metric: { list: [ 'AA', 'BB' ] },
  metricList: [ 'CC', 'DD' ],
  '$0': 'yargs-example.js' }