MOVIE PREMIERE or SERIES FINALE: Take your pick, because this new NBC Timeless “movie,” actually consisting of two one-hour episodes, serves both functions. It’s a telemovie premiere, because it’s a stand-alone story, called “The Miracle of Christmas.” And it’s a way for this time-travel cult series – which presented its last installment when NBC canceled it in May – to take time, so to speak, to end with a proper finale. Lucy and Wyatt get s