chore: un-deprecate firstDayOfWeek

[J-Sek]

Looking a this after a while.. users sometimes get a dropdown to change week start - overriding their locale preferences. It is a valid scenario and I don't see any way to achieve this with VLocaleProvider

[johnleider]

What does all of this look like in the precursor to Temporal taking over date stuff? Are we able to do this in a way that regardless of what adapter the developer uses, it will work?

[J-Sek]

What does all of this look like in the precursor to Temporal taking over date stuff? Are we able to do this in a way that regardless of what adapter the developer uses, it will work?

Option 1: Keep disclaimers about "no guarantee" to work with custom adapters and rely on developers to extend the adapter class (we have a minimal guide in the docs, but we could add more with copy-pastable snippets).

Option 2: Introduce a proxy around the adapter so we can detect non-empty firstDayOfWeek argument and redirect method calls to our internal implementation.

[johnleider]

I like Option 2 as long as it can be a small code footprint and require zero changes from the user.

[J-Sek]

roduce a proxy around the adapter so we can detect non-empty firstDayOfWeek argument and redirect method calls to our internal implementation.

Do you need a PoC before we merge this PR?