Use correct timezone when parsing date in json

[arnvald]

Fixes #22171

Time specified in ISO 8601 format without Z should be parsed as local time, yet until now it was treated as UTC.

This commit fixes problem by parsing time using timezone specified in application config.

The downside of this solution is performance hit (Time.zone.parse is ~ 1.6x slower than Time.parse), so maybe there's a better solution.

Additionally, YYYY-MM-DD format is parsed as Date not DateTime as it was until now (recommended by @pixeltrix #22171 (comment))

/cc @maclover7 @pixeltrix @chancancode

[rails-bot]

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[pixeltrix]

@arnvald this looks good 👍

Can we add a CHANGELOG entry - thanks.

[arnvald]

@pixeltrix thank you! I've rebased the branch and updated changelog

[prathamesh-sonpatki]

@arnvald Newly added CHANGELOG should be added at the top of the file. Please move this entry to the top of CHANGELOG file.

[arnvald]

@prathamesh-sonpatki updated, thanks for information! :)

[chancancode]

@arnvald omg! so sorry for the delay, I have merged this in 3a9428d

@rafaelfranca @sgrif @eileencodes should this be backported to 5-0-0 or 5-0-stable? I would like to get this on 5.0.0 if possible because it is technically a breaking change (the class changed from Time to Date in some cases), and I would like to not do that in 5.0.0 rather than 5.0.1 (or we can leave this for 5.1.0 I suppose)