direShell calling quit is evil: instead should throw a (sub)class of CatcheableError

[timotheecour]

/cc @yglukhov @fowlmouth

see also https://forum.nim-lang.org/t/4042#25152: (quit considered evil: bypasses defer and try/catch/finally which might do important cleanups)

eg in $nim_D/nimx/nimx/naketools.nim it prevents doing things like:

try:
  direShell "xcodebuild", "-project", xcodeProjDir/"SDL.xcodeproj", "-target", "Static\\ Library", "-configuration", "Release", "-sdk", "macosx"&b.macOSSDKVersion, "SYMROOT=build"
except CatchableError as e:
  # process e, give an informative msg (eg to suggest alternatives like brew install sdl2), or provide fallback options