Some opener commands (like macOS's open) finish immediately after
running, while others (xdg-open) do not, staying alive until the
application that was opened itself terminates.
For now, we explicitly state whether or not we should wait for a
command. Eventually we may want to do something more generic (e.g. wait
for some predetermined amount of time and if the process does not
complete, give up without collecting stderr).
This gets `zig build -Dtarget=aarch64-ios` working. By "working" I mean
it produces an object file without compiler errors. However, the object
file certainly isn't useful since it uses a number of features that will
not work in the iOS sandbox.
This is just an experiment more than anything to see how hard it would be to
get libghostty working within iOS to render a terminal. Note iOS doesn't
support ptys so this wouldn't be a true on-device terminal. The
challenge right now is to just get a terminal rendering (not usable).
