feat: added Date optics

[jessekelly881]

Added data/Date with Lenses for year, month, day, hour, minute, second, and millisecond.

[gcanti]

What's the meaning of the utc parameter? Intuitively looking at just the signature, I would have thought "use UTC", but from the code it doesn't seem to be the case.

[jessekelly881]

Most of the js Date functions have UTC equivalents that (I believe) set the hour, day, etc. as if it were that hour/day UTC time and then converts the result back to local time. If the date is already in UTC time, calling setHours(2) will just update the time to 2am. But if the date is UTC - 1 for example it will set the hour to 1am(local time). I will update the docs and tests to make it a bit clearer what's going on. https://stackoverflow.com/questions/32647928/setutchours-adds-an-hour-to-time-passed-to-the-function

[IMax153]

@jessekelly881 I'm not sure that the proposed API is necessarily desirable. I would almost argue that we should just treat every date the same and avoid calling the setUTC* variants internally. If the user want to use UTC, then their input Date to the optic should be in UTC.

[jessekelly881]

Ok. I'm inclined to agree. I'll update the pr. Do we prefer Date.hour() or Date.hour?

[IMax153]

I'll leave that question for @gcanti 😃

[gcanti]

Do we prefer Date.hour() or Date.hour?

hour

[jessekelly881]

Cool! I updated it.

[gcanti]

Thanks @jessekelly881 @IMax153