Create a 10-bit ImageRgbU10 image format

[Dawoodoz]

To get a higher range of brightness for post processed images, or simply get more precision in baked normal and position maps, it would be relatively easy to create a 10-bit format when channels are already accessed using masking and shifting.

Having RgbaU8 defined by byte indices and RgbU10 defined by bit significance would however make little sense. Would have to redefine the relation between endianness and pack order, so that color channels are ordered by bit significance instead of byte order. Then the channel indices in PackOrder need to change for big-endian instead of the direction of bit shifts.

Dynamic pack orders would not exist for RgbU10, because it will not be used in any window canvas.

To reduce duplicated code, the entire framework needs to be streamlined for template programming with minimal risk of ambiguity.

Static inheritance can be used to define a 10-bit type masked to 10 bits on assignments and padded to 16 bits when stored.