v1.2.0-beta2: OBS and Windows fix

(This is a fix for the previous beta1 for OBS and Windows compatibility. Unfortunately, it has to sacrifice some bandwidth and no longer reaches 60fps. But it brings back green mode.)

Thanks to @Ikadzuchi's brilliant suggestion for a simplified method to encode MJPEG (see #17) and @kkitayam's implementation of bulk transfer mode for the USB Video Class in Tiny USB this release implements lossless MJPEG video instead of the original raw NV12 encoding. This in particular introduces two major features:

• Almost 60fps (something around 56fps, not quite there)
• Full Apple compatibility (Intel-based Macs have been working before, but now M1/M2-based ones seem to be happy as well)
• Overall better compatibility with software, in particular with many more Android apps than before.

However, this comes with some drawbacks, which I think are a minor inconvenience at best and which should be fixable in post or the streaming software (i.e. OBS):

• Because of Ikadzuchi's trick, the host device sees an image that is scaled up by a factor of 8, i.e. 1280x1152. (Since this is still less than typical FullHD, most host devices should handle this without a problem and be able to scale it back down if required.)
• Frame blending is now limited to blending two subsequent frames in equal parts (which looks better in most flicker-transparancy situations anyway - as before you can disable it with the button next to the LEDs).
• Contrast is slightly reduced (easily fixed in post or OBS).
• Serial interface has been dropped (as far as I know only I use it for debugging and it interfered with bulk transfer speed).

Please be aware that this here is a test version that I would not recommend for a new build when you are not yet sure if your Interceptor is working correctly. However, if you already have a working Interceptor, please test this version and report back if it works for you! Changing to MJPEG and bulk transfer are major changes from a technical point of view and I cannot test all combinations before placing this in the official release.

In particular I would like to get feedback on:

• Mac compatibility
• Compatibility with your workflow and the software you use
• Super Game Boy compatibility (since it runs a bit faster than 60fps and I do not have one to try it)

Game compatibility should be the same as before.