Fix VC++ dependency requirement on windows hosts

[eddymoulton]

When implementing #8, we accidentally lent on VC++ being installed on Windows hosts which wasn't picked up because it is often pre-installed.

This change:

• Splits the build up into win, linux and mac jobs so we get a faster feedback loop
• Modifies the windows build to generate a static binary that includes libssh2 + further dependencies
  • This mirrors the fix we did for OpenSSL 1.1
• Adds a smoke test to ensure that the windows (and linux) binaries are able to be loaded on images that do not have pre-installed prerequisites.
  • Before the fix was applied, I confirmed the smoke test fails

I'll come back and make the same change for openssl3 linux builds too but for now this is blocking a windows release.
The Linux change will involve more testing, so best not to rush it.

Relates to MD-2027

[eddymoulton]

These two properties are new