Templating: week number in templates should use NP API to get NP week, not isoWeek

There are convenience functions in templates that get the weekNumber, e.g.

  weekNumber(pivotDate = '') {

@EduardMe has added functionality to get the NP week number instead, since iso may or may not match what you see in your NP interface, depending on what day you pick for the beginning of a week.

For example, here's how I told a user recently to do it:

---
title: Weekly Note Template Tag
---
Using now/today, no matter where you are, this gives you the current weekly note:
[[<%- Calendar.weekYear(new Date()) %>-W<%- Calendar.weekNumber(new Date()) -%>]]
output: 2022-W49

Using week date (this is the best one if you want the weekly note corresponding to a Calendar note which doesn't have to be today):
[[<%- Calendar.weekYear(Editor.note.date) %>-W<%- Calendar.weekNumber(Editor.note.date) -%>]]

Using title (should normally work as above:
[[<%- Calendar.weekYear(new Date(Editor.note.title)) %>-W<%- Calendar.weekNumber(new Date(Editor.note.title)) -%>]]

@jgclark You deal with these kinds of things more than I do. What other things like weekNumber should be fixed/added to the templating date module to give users access to this info?