Shamelessly copied the FP32 -> B10G11R11 and FP32 -> E5B9G9R9
conversion functions from Angle. This allows packing the clear
color for these formats into a single 32 bit integer, which can
then be used within the fast clear function.

Tested using:
api.image_clearing.core.clear_color_image.*.b10g11r11_ufloat_pack32
api.image_clearing.core.clear_color_image.*.e5b9g9r9_ufloat_pack32

Bug b/119620767

Change-Id: Ic268da62959582f084245e88181374213734760f
Reviewed-on: https://swiftshader-review.googlesource.com/c/23650Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Corentin Wallez <cwallez@google.com>