private int computeCharOffset(int col) {
		if (col >= byteGroupSize * CHARS_IN_BYTE) {
			return col - ((byteGroupSize - 1) * CHARS_IN_BYTE);
		}
		return col % CHARS_IN_BYTE;
	}
Computes the character offset for a BytesFieldLocation based on the character column the
cursor is at in the token.  BytesFieldLocation character offsets are always as if the group
size is 1. So for all positions except the last byte, it is just the column modulo 2.  For
the last byte, we have to account for any columns past the last char.  In this case, we have
to subtract off 2 for every byte before the last byte.
Ghidra/Features/Base/src/main/java/ghidra/app/util/viewer/field/BytesFieldFactory.java