v1.2.0-beta1: 60fps and Apple compatibility

This version has severe compatibility issues (the irony) on Windows and OBS.
Please use the newer beta2 instead

Original release notes

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](https://github.com/hathach/tinyusb/pull/1985) this release implements lossless **MJPEG** video instead of the original raw NV12 encoding. This in particular introduces two major features:

• True 60fps (well, the exact frame rate that the Game Boy delivers, so something like 59.7Hz)
• 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):

• Green mode is no longer available (might technically be possible, but would be a bit of a headache and filters in post should give better results anyway)
• 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).

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
• Windows compatibility (being a Linux guy I have not tested it)
• 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.