CI: Use MSVC 2022 and update Lua/Luarocks versions

[squeek502]

This essentially treats MSVC 2015 as the minimum supported version, and updates the Appveyor CI to use MSVC 2022 to do all the Lua/Luarocks tests. From #586:

I'm thinking about keeping the current 2015 tests, and then moving the rest to just use 2022. That way we can ensure we maintain a minimum supported MSVC (2015) and ensure that we build using the latest version. We won't ensure that the in-between versions will still build properly, but it seems somewhat unlikely that we would introduce problems specific to an in-between version.

Closes #586