feature/mx-1569 Distinguish date (Year-Month-Day) from Year-Month or Year

[carolinscholl]

PR Context

To improve date validation, we need to distinguish between dates (with format YYYY-MM-DD) and partial dates like only YYYY or YYYY-MM. That is why there is now a new type for these partial dates.

Added

• new partial date type (for YYYY or YYYY-MM formats)

[fdiehr]

look good, but I wonder, if it makes more sense to define some field schemas (mex/model/fields) for the different date types (datetime and date with the different patterns). then we wouldn't need to define the respective fields in each entity schema and each property, but reference the specific date type field. what do you think?

[cutoffthetop]

look good, but I wonder, if it makes more sense to define some field schemas (mex/model/fields) for the different date types (datetime and date with the different patterns). then we wouldn't need to define the respective fields in each entity schema and each property, but reference the specific date type field. what do you think?

as discussed in a call: i think that is not really worth it since we already have 3 different combos of accepted date/times that fields accept (date, datetime, datetime+str)