Give \addlyrics the power of christening the associated context

Give \addlyrics the power of christening the associated context

With

\new Voice \with { \stemDown } { c1 } \addlyrics { Oh }

as opposed to

\new Voice = "upper" \with { \stemDown } { c1 } \addlyrics { Oh }

\addlyrics created its own context (consequently not using \stemDown)
since it had no context name for the Lyrics context to attach to.  In
this case (namely being preceded by an unnamed new Voice context), it
will now give a name to the context itself.