tool to halve/double the timing of a selection of notes?

ive created an initial score like below.
now I have realized that I got the tempo wrong. it should be half this speed. which means taking every note here to a lower level (half-notes to quarter-notes, quarter-notes (and rests) into eighth-notes (and rests) etc).
I don't see a way to achieve this currently. this means I have to restart the whole project just to halve the time.
is there a built function/shortcut for this? if there isn't, can it be built? allow it for a highlighted selection, as the user can just move the other notes out of the way.

thanks
avi
p.s. I've had a similar problem with realizing that a 4/4 should be a 12/8 time, then had to restart the whole thing, as opposed being able to adapt (and fix) the score. but I feel like this is a much taller ask, then just being able to halve/double the note-properties)