Use CGImage instead of NSBitmapImageRep (bug#32932)

Use CGImage instead of NSBitmapImageRep (bug#32932)

* src/nsterm.m (ns_update_end):
(ns_clear_frame): Remove forced draws.
(ns_draw_fringe_bitmap):
(ns_dumpglyphs_image): No longer need to invert images as the context
is already flipped.
([EmacsView updateFrameSize:]):
([EmacsView initFrameFromEmacs:]): Use new function.
([EmacsView createDrawingBuffer]): Replaces createDrawingBufferWithRect:.
([EmacsView focusOnDrawingBuffer]): Set CGImage context.
([EmacsView windowDidChangeBackingProperties:]): Use new function.
([EmacsView copyRect:to:]): Copy using CGImages.
([EmacsView wantsUpdateLayer]):
([EmacsView updateLayer]): New Functions.
([EmacsView drawRect:]): We no longer do anything special here for
Cocoa.
([EmacsView windowDidChangeBackingProperties:]): Fix indentation and
add NSTRACE.