Continuing the theme, add 3 MSVC jobs with tests, matching
configurations used on AppVeyor. MSVC versions are identical:
19.39.33523.0 + Windows SDK 10.0.22621.0.
Also enable websockets, and build examples. Tests are run in parallel
(`-j14`), with improved performance.
Job performance:
```
AppVeyor GHA
w/examples
-------- ----------
CMake, VS2022, Debug, x64, Schannel, Static, Unicode 38m 4s 11m57s
CMake, VS2022, Debug, x64, no SSL, Static 35m15s 12m 6s
CMake, VS2022, Debug, x64, no SSL, Static, HTTP only 25m25s 10m36s
```
Based on these runs:
https://ci.appveyor.com/project/curlorg/curl/builds/49884748https://github.com/curl/curl/actions/runs/9229448468
This is the first time examples are built in CI with MSVC: Fix all
warnings and errors that came up via
d4b8589055#13771.
Closes#13766
c8f61dbba6