Add RGB color ordering a la Arduino library, FrameBuffer copy via image()

[PaintYourDragon]

Principal change here is the addition of different RGB byte orders, to provide compatibility with the initial batch of STEMMA QT matrices and also future-proof against possible future changes to RGB LED pinouts. All of the high-level class constructors (ISSI_EVB, Adafruit_RGBMatrixQT and LED_Glasses) accept an optional “order” argument, with a similar color order to the Arduino library:
matrix = Adafruit_RGBMatrixQT(i2c, order = adafruit_is31fl3741.IS3741_RBG)
The default order if unspecified is IS3741_BGR, compatible with ISSI eval board, currently-shipping QT matrices, and EyeLights glasses.
The initial batch of QT matrices had a different type of LED: use IS3741_RBG there.

Tested against Arduino library, all color orders work similarly, both in direct and buffered modes.

Additional change is that in CircuitPython the image() function accepts a FrameBuffer object. Since the IS31 library itself doesn’t provide any drawing primitives, one can use adafruit_framebuffer instead, then image() the result to the RGB matrix. (Haven't benchmarked, but potentially faster in some situations.) It’s primitive and doesn’t trap mismatches — the FrameBuffer and matrix need to be the same size — but it’s a start.

Additionally, the pixel-setter function may be a smidge faster now, some bounds checks weren’t necessary.

[github-actions]

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