A version of `whisker::whisker.render()` that more closely aligns with `epoxy()`?

[gadenbuie]

epoxy_mustache() that corresponds to ui_epoxy_mustache()? It would have slightly better semantics than whisker.render():

• Takes ... and does the same thing as epoxy() re named/unnamed arguments.
• Better aligns with Shiny's idea of truthiness, e.g. "" and NA are missing rather than counting as being included.
• Might have to apply the same truthiness filter to render_epoxy()? Or opt-in and enabled for ui_epoxy_mustache() by default.