Add native transformations for rounding a dateTime

[Seddryck]

At the moment, it's possible to round a dateTime at the level of year or month (dateTime-to-first-of-year, dateTime-to-last-of-month ...) it's also possible at the level of the day with dateTime-set-time(00:00:00) but not at the level of the hour or minute.

It should be possible to transform the value 2019-08-24 10:49:12 to 2019-08-24 10:00:00 or 2019-08-24 11:00:00 (floor or ceiling).

• dateTime-to-floor-hour
• dateTime-to-ceiling-hour
• dateTime-to-floor-minute
• dateTime-to-ceiling-minute

[Seddryck]

Beta available in 1.21.0-beta0286