Adding dayPeriodPatterns

[rotsee]

We had cldr.extractDayPeriods(), but no method to extract the day period patterns that they are often used with. Here's an attempt to add that method.

[coveralls]

coverage: 76.44% (+0.2%) from 76.22%
when pulling d10a582 on dayperiodrules
into 2d9ddc0 on master.

[papandreou]

I see that the prettier setup is out of order, taking the liberty of applying my suggestions and merging this so I can fix it 😇

Edit: Sorry, it was my prettier editor plugin that was out of order.

[papandreou]

Released in 7.9.0.