Convert deprecated cython extension class properties to new syntax part 4

[JoeSchiff]

I had some trouble with the color_range property in av/video/codeccontext.pyx and tests/test_colorspace.py.

After my changes, stream.color_range now returns 2 instead of None and therefore fails the test. I have no idea which one is actually correct.

Here is some additional context which may or may not be related:

1. I get this warning when opening the file used in tests/test_colorspace.py:
   container = av.open(fate_suite("amv/MTV_high_res_320x240_sample_Penguin_Joke_MTV_from_WMV.amv"))
WARNING libav.avi:test_colorspace.py:9 scale/rate is 0/0 which is invalid. (This file has been generated by broken software.)

2. The color_range property in av/video/codeccontext.pyx had unusal syntax. The decorator was used, but so was __get__ and __set__.

3. There are two color_range data fields in ffmpeg:
   AVCodecContext::color_range
   https://ffmpeg.org//doxygen/6.0/structAVCodecContext.html#a255bf7100a4ba6dcb6ee5d87740a4f35
   AVFrame::color_range
   https://ffmpeg.org//doxygen/6.0/structAVFrame.html#a853afbad220bbc58549b4860732a3aa5

I'll do more research in the next few days, unless the solution is obvious to someone already.

[WyattBlue]

I think 2 is correct and None is wrong. The old color_range getter looks like it incorrectly always returns None.

[JoeSchiff]

WyattBlue, testing with ffprobe confirms that you are correct. It feels good to unexpectedly squash that bug.