[4.4] Determine the next task run date with the timezone of the site

[laoneo]

Summary of Changes

When using Cron expressions in a task, then they are always executed in UTC timezone. This leads to an issue when the cron ob should run on a specific time on the day and the Joomla site is in a timezone where the there are DST changes. This pr calculates the next run date according to the timezone of Joomla and displays the next execution date in the same time when editing the task (it is the same time as in the tasks list then).

Testing Instructions

• Define a timezone in Joomla, other than UTC
• Create a new sleep task and define a cron expression like
  
• Open the execution history tab

Actual result BEFORE applying this Pull Request

It shows the UTC time as next execution date.

Expected result AFTER applying this Pull Request

It shows the correct time as next execution date.

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[hytsch]

checked, works fine, thanks :)

[fgsw]

I have tested this item ✅ successfully on 2a56945

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43259.}

[Quy]

@laoneo Please fix phpcs. Thanks.

[MacJoom]

Thank you!