Teach the script to indicate what is different on failure rather than
keeping quiet. This helps when the script is failing in CI but not
locally.
### Motivation:
The script is reporting that there are missing changes in CI on
swift-crypto, but I am unable to reproduce them locally. This is to get
immediate insight on why the check fails rather than keeping quiet.
### Modifications:
Include the diff in the update-cmake-lists script.
### Result:
update-cmake-lists script outputs the difference between what is in a PR
vs what it expects to see instead of shrugging and leaving it as an
exercise to the user.
Add assembly files for Windows
### Motivation:
These assembly files are now required to build on Windows Arm64.
### Modifications:
* The Windows assembly files are now handled in `update-cmake-lists.sh`.
### Result:
The assembly source files will be properly updated in `swift-crypto`.
### Motivation
A few repositories have custom workflows for checking CMake, we would
like to unify this for maintenance and adoption simplicity.
Further to this at the moment they only check that the scripts are
up-to-date, we'd also like to have them build using CMake.
### Modifications
Add the re-usable workflow and supporting scripts
### Result:
Repositories using CMake can switch to the centralised workflow.
An example of it in action
https://github.com/apple/swift-crypto/actions/runs/13837092514/job/38782284575
Evan Wilde
Fabrice de Gans
Rick Newton-Rogers