Visualise C++20 chrono additions

[SuperWig]

• Added singular forms of durations (second, minute, etc.)
• Added visualisations for the new calendar types.
• It looks like this
  

Thoughts and questions

• The 1st/2nd etc could probably be dropped on day?
• The _last types might be better without the "Last"s?
• is_negative should probably be dropped?
• This is the first time I've messed with natvis' and couldn't find a way to specify a width, is that not possible? Seems a bit hacky the way I did it and should that be used for the calendar types as well to use the ISO date format (YYYY-MM-DD)?

[CaseyCarter]

For the record, I'm ok with st/rd/th and Last. They're not localized, but then neither is the rest of this.

[StephanTLavavej]

Apologies for the late review. I noticed one inconsistency in the display string (followed by a simplification). I haven't tested my suggested changes. I'm OK with proceeding to merge without addressing this feedback. However, if these changes are correct and you want to apply them, make sure to update the MSVC and VS PRs too.

[StephanTLavavej]

Thanks @SuperWig for these awesome visualizers and thanks @AnjuDel for merging this to the internal repos! 🎉 👁️ 📆 😸