Workaround for enabling 1080p streaming from linux

[satmandu]

As per @Varstahl suggestion here: #218 (comment)

This is working in official Kodi 18 Linux nightlies for streaming of Prime TV series in the US.

Also as suggested for this issue here: #205 (comment)

[Varstahl]

Glad it works for so many of you, and props to @Paco8 for finding it out.

Before actually merging it though, I want to investigate these new API parameters.
It could possibly solve some of the FHD decoding issues we were experiencing so far. Could be worth a shot.

[Varstahl]

After a few tests, selecting anything other than Windows (and a few other written below), with this specific capitalization, reduces the number of videos available for playback. If, for example, we select Linux, it hides all the high movie resolution streams (that are unplayable anyway, in our case), but along with it takes a few of the high resolution TV series that would be playable. Using the Windows parameter, seems to restore all video qualities.

With a bit of data mining, and several tests later, I found the following:

operatingSystemName	Max. playable	Max. available
Unknown	1088x464
Android	1088x464
BlackBerry	1088x464
Chrome OS	1088x464
Firefox OS	1088x464
Google TV	1088x464
iOS	1088x464
Linux	1088x464
Mac OS X	1088x464	1920x816
Mac OS PPC	1088x464
Windows	1088x464	1920x816
Windows Phone	1088x464
Windows RT	1088x464	1920x816
Xbox One	1088x464

As far as movies go, Mac OS X, Windows and Windows RT have the full 1920 width available, although at least on my Win7 machine, only streams up to 1088x464 were playable. Anything higher would result in audio and a freezed frame. All streams reported as H264.

All these tests have been done without the operatingSystemVersion. I'm mostly sure to have seen some hardcoding about a version 10.12 inside the Javascript, maybe it will yield different outcomes, but that will require more poking, prodding and reverse engineering. I'll update the post if I find something new. They were mostly for Safari, Mac and HLS/Avci streams. Completely useless and changed basically nothing of our situation. Rien à faire…

For the time being I'll validate this as a universal fix, since it works on both PrimeVideo.com, Amazon.TLDs, Android, Linux and Windows.