Add a detailed date and time format option

Ondrej Holy requested to merge wip/oholy/detailed-date into main

The default time and date formats in Files are intended to be human friendly and to avoid information overload. This works for most cases and is an appropriate default. However, there are cases where people need to be able to see a complete date and time for their files. Let's add a user preference to show a more detailed date and time format.

Resolves: #2874

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