Update CMake min to 3.28

[jpr42]

Ubuntu 24.04 LTS (noble) packages cmake 3.28.3, only the 2 latest LTS releases are supported,
requiring 3.28 keeps compatibility with all currently supported Ubuntu LTS versions.

Utilize new block() functionality instead of function

Utilize VERIFY_INTERFACE_HEADER_SETS to ensure header files can compile correctly on their own. (Test code only).

[CLAassistant]

All committers have signed the CLA.

[M2-TE]

Should already be good in its current state.
Still, I've added two minor comments below.

Another thing: The windows clang runners only seem to use the latest default cmake, not [ '3.22.1', 'latest'] like the others. Is this intentional?

[jpr42]

Another thing: The windows clang runners only seem to use the latest default cmake, not [ '3.22.1', 'latest'] like the others. Is this intentional?

Not sure. I fixed it regardless.

[M2-TE]

Looks good. Got nothing else to add!

[charles-lunarg]

Wow it felt like CMake 3.28 released last week... it came out at the tail end of 2023.

Looking through various Vulkan repo's, the min cmake version is 3.22.1, which stems from an update to spirv-tools that occured in Jan 2025.

I am going to approve this PR because it is in a good state, and moves the baseline forward, but I am holding off merging until I can get a confirmation that it is too soon to update. Merging this will likely require dependent repo's to update their CMake version, so in a sense this triggers a small cascade of subsequent PR's in about a dozen repo's.