i18n: Supply date/time parameters to some messages

Date/Time parameters added to messages:
* wikiforum-by (Deprecated $1, using date/time)
* wikiforum-posted (Deprecated $1, using date/time)
* wikiforum-edited (Deprecated $1, using date/time)

Spotted by Purodha:
* https://translatewiki.net/wiki/Thread:Support/GENDER_support_and_date_and_time_parameters_needed

Change-Id: I405cf7fa3fadbc71b6cf2a4f1782c2ef8be0c226
Merge "i18n: Supply date/time parameters to some messages"