This PR adds conversion template to convert between Low Precision float
formats. These include Binary32 floats and lower. It also adds support
to convert between unsigned and signed float formats and float formats
with different mantissa and exponents.
Additionally overflows (values that don't fit in the target float
format) will be clamped to the maximum value.
**Reasoning**:
Up to now the Vulkan backend only supported float and half float
formats, but to support workbench, 11 and 10 unsigned floats have to be
supported as well. The available libraries that support those float
formats targets scientific applications. Where the final code couldn't
be optimized that well by the compiler.
Data conversion for color pixels have different requirements about
clamping and sign, what could eliminate some clamping code in other
areas in Blender as well. Also could fix some undesired overflow when
using pixels with high intensity that didn't fit in the texture format
leading to known artifects in Eevee and slow-down in the image editor.
**Future**
In the future we might want to move this to the public part of the GPU
module so we can use this as well in other areas (Metal backend), Imbuf clamping
See 3c658d2c2e69e9cf97dfaa7a3c164262aefb9e76 for a commit that uses
this and improves image editor massively as it doesn't need to reiterate over
the image buffer to clamp the values into a known range.
Pull Request: https://projects.blender.org/blender/blender/pulls/108168
b7963d247c