At least in MSVC (which is not restricted from targetting C++20), these can be resolved to either std::format_to or fmt::format_to (though I'm not sure why the std one is available).  We want the latter.

fmt 8.0.0 requires this.

SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.

Zero-initialization zeroes out all members and padding bits, so this is
safe to do. While we're at it, also add static assertions that enforce
the necessary requirements of a UID type explicitly within the ShaderUid
class.

This way, we can remove several memset calls around the shader
generation code that makes sure the underlying UID data is zeroed out.
Now our ShaderUid class enforces this for us, so we don't need to care about
it at the usage sites.

Also moves logic for primitive handling to VideoCommon.