New relative timestamp that matches embed timestamps

[ssesfahani]

It would be nice to have a timestamp style that matches the embed rendering, showing yesterday or today or the date it if it's further out than that.

[Neodevils]

Adding a smart timestamp style to message formatting that mirrors embed behavior would solve this neatly of course.

If the existing timestamp syntax <t:unix:style> had a new style (for example, S) that renders "today" when the timestamp falls within the viewer's current calendar day, "yesterday" for the previous day, and otherwise shows a localized short date (same as d), using the viewer's timezone. Yeah, this this can be done.