support for the options of decoding quality of videotoolbox

[ponpon]

thank ffmpeg team for the good app.

as i said in the ticket #5272, seeing
"/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/System/Library/Frameworks/VideoToolbox.framework/Versions/A/Headers/VTDecompressionProperties.h"
videotoolbox decoder has the options of decoding quality.

there is a commit of such a function in vlc player.
[vlc-commits] videotoolbox: add temporal deinterlacer option
​​https://mailman.videolan.org/pipermail/vlc-commits/2015-August/031929.html

i request supports for the below options.
for denterlace
kVTDecompressionPropertyKey_FieldMode
kVTDecompressionPropertyKey_DeinterlaceMode

for scale
kVTDecompressionPropertyKey_ReducedResolutionDecode

for frame drop
kVTDecompressionPropertyKey_ReducedFrameDelivery
kVTDecompressionPropertyKey_OnlyTheseFrames

for realtime playback
kVTDecompressionPropertyKey_SuggestedQualityOfServiceTiers

though there are some options pixel formats and kVTDecompressionPropertyKey_ReducedCoefficientDecode, i don't evaluate these.