[Feature request] MSIX back-end to CPack (CMake)

It was suggested that I file an issue/request on this repo. IMHO it would make an enormous difference if MSIX could leverage all the CMake scripts in the wild as easily as reasonably possible. I'm aware of the ability to go through WIX (which isn't free) but also isn't a viable option for many mega and useful projects, starting with the likes of LLVM, Doxygen and CMake itself. (I know, developers always think of themselves first.)

Jokes aside, CMake having as large of a marketshare as it does, it would be a huge facility, if CPack would have a proper MSIX generator back-end. Hooking up the MSIX SDK to CMake is very much doable, but definitely non-zero amount of work. MS implementing said back-end, or simply just hiring Kitware to make it happen would have a positive impact on the momentum behind MSIX.

My previous attempts at trying to create Store-compatible packages using the command-line tools have all failed miserably. (Some errors summarized here.) Some tooling around producing/publishing MSIX packages outside MSBuild/Visual Studio is direly missing. Either CMake modules, but more importantly proper CPack support.

Start by reviewing CPack's existing generator architecture and the MSIX SDK and command-line tooling referenced in the issue. Determine the integration boundary and packaging requirements, then define how proper CPack support would produce Store-compatible MSIX packages and how that result could be validated.