vulkan/wsi/sw: wait for image fence before submitting to queue

With hw devices, when you submit a present, implicit sync will make sure the work submitted to the gpu on the client will end up happening before the present work submitted on the server.

However with sw paths there is no real GPU, the lavapipe fake GPU thread is client side only and presenting is done directly from the pixmap (or later shared pixmap). In order for this to make sense the wsi common code should wait for the fence on the image before queueing the submit to the server so that all client works has been flushed to the pixmap before the copy or present operation is submitted.