dayjs fix: offset calculation of timezone plugin

Update calculation of timezone offset. This change was caused by this issue https://github.com/iamkun/dayjs/issues/2207. The thing is that Hermes in React Native doesn't fully support Intl API (https://github.com/facebook/hermes/issues/23). Let me explain.

This code:

const target = date.toLocaleString('en-US', { timeZone: timezone })

works correct, it returns the date in en-US format, but after that when returned string is passed to Date constructor it returns Date { NaN }:

const target = date.toLocaleString('en-US', { timeZone: timezone })
new Date(target) // Date { NaN }

Date constructor cannot recognise this format, so calculation of difference is broken. And I think that we can use dayjs to do backward formatting.

Note: in my opinion we can improve somehow the calculation of timezone offset not to depend on some APIs support (get rid of Date.toLocaleString).

Feb 05 '23 19:02 Pareder

Codecov Report

Patch coverage: 100.00% and no project coverage change.

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Additional details and impacted files

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