add ISO year / ISO week utilities (#48507)
Based on some discussion in
https://discourse.julialang.org/t/determine-date-range-given-year-and-week-number/93878
and the relevant issue https://github.com/JuliaLang/julia/issues/48490
I created a couple of utilities to help handle 2023-W05-4 (YYYY-WWW-D)
dateformats (https://en.wikipedia.org/wiki/ISO_week_date)
Currently there is no functionality of ISO Week with weekday |
2023-W05-4 in Julia, but this could be good start and could help a lot
of people who require such dateformat.
Notably, with `firstmondayofyear` it is trivial to convert from week
format 2023-W05-4 to usual date format 2023-02-02 as:
```
firstmondayofyear(Date(2023)) + Week(5 - 1) + Day(3)
```
This was otherwise impossible within std lib
---------
Co-authored-by: Jeremie Knuesel <knuesel@gmail.com>
Co-authored-by: woclass <git@wo-class.cn>
Co-authored-by: Viral B. Shah <ViralBShah@users.noreply.github.com>
Co-authored-by: Andy Dienes <51664769+adienes@users.noreply.github.com>
