Fixes #1480. Convert DateOnly properties to local timezone

[Shaddix]

Fixes #1480

[RicoSuter]

If this PR should still be merged, please fix the conflicts and we'll have a look at it.

[Shaddix]

conflicts are fixed

[RicoSuter]

Thanks for the PR.

[wuzzeb]

I think this PR doesn't completely fix the issue of dates and timezones, because serialization always assumes a local timezone.

Thus, if the setting ConvertDateToLocalTimezone is false, the parsing code will use new Date("2023-09-21") which assumes UTC but the formatting code calls formatDate (https://github.com/RicoSuter/NJsonSchema/blob/master/src/NJsonSchema.CodeGeneration.TypeScript/Templates/File.FormatDate.liquid) which uses d.getMonth() etc which assume local timezone.

This means if ConvertDateToLocalTimezone is false, you can parse and then immediately convert back to JSON and get a different result.

There should also be a formatUTCDate function which uses instead getUTCMonth and friends, because dates are assumed to be in UTC.

Then, when ConvertDateToLocalTimezone is false, the generated toJSON function should use formtUTCDate instead of formatDate.

Then, both the serialization and deserialization will both use the same expected format and you can serialize followed by a deserialize without changing the data.