faster cairo paint: avoid copying pixels whenever possible

[totaam]

We can use ImageSurface.create_for_data if the pixel data stride satisfies stride_for_width
Another undocumented constraint is that the memory must not be read-only..

[totaam]

With the latest test, we report the performance of each call to make_image_surface.
Unsuprisingly, the zero-copy options are way faster:

RGBA to cairo.ARGB32 :   162 MPixels/s
RGBX to cairo.ARGB32 :   156 MPixels/s
BGRA to cairo.ARGB32 :  4543 MPixels/s
BGRX to cairo.ARGB32 :   179 MPixels/s
RGB  to cairo.ARGB32 :   170 MPixels/s
BGR  to cairo.ARGB32 :   152 MPixels/s
RGBA to cairo.RGB24  :   192 MPixels/s
RGBX to cairo.RGB24  :   193 MPixels/s
BGRA to cairo.RGB24  :  4529 MPixels/s
BGRX to cairo.RGB24  :  4535 MPixels/s
RGB  to cairo.RGB24  :   192 MPixels/s
BGR  to cairo.RGB24  :   171 MPixels/s

So we should really make sure that the cairo backend tells the decoder modules to provide BGRA or BGRX, not RGB or BGR even if they take up less space..
(the OpenGL backend doesn't care - the pixel upload functions support every format)

[totaam]

Changing the decoders to prefer BGRX / BGRA:

• video via csc modules: 793ee3f
• avif already OK:

  xpra/xpra/codecs/avif/decoder.pyx

  Line 144 in e2142ad

  rgb_format = "BGRA"

• spng only supports RGBA / RGBX (wrong byte order), we normally prefer webp anyway:

  xpra/xpra/server/window/compress.py

  Line 1145 in e2142ad

  if depth in (24, 32) and (jpeg or jpega or webp or avif):

• webp: 398e510
• jpeg: e2142ad