Add arm color conversions for the vertex decoder jit

May not be the most perfectly optimal, but they seem to work okay (I'm least confident about 5551, but I'm sure about the others.)

I tried LDMIA/STMIA, they worked great for me.  However, they only work on aligned addresses AFAIK.  Not sure if that's a problem.  Maybe we can at least use STMIA?  I left the code in but commented out.

Note: the I2Rs in the jit code are for readability.  None of them should actually be using anything but and Operand2.  Also, I got confused, it'd be nice if it was a compile time error to pass an imm that's outside a u8 if it's not gonna auto-shift, took me a while to realize why 0xF000 didn't work and switch to I2R...

With this, Dissidia at least seemed faster to me, but I forgot to carefully time it.  Before it was spending a lot of time in the vertex step funcs per a profile (due to Color4444.)

-[Unknown]