Add depfile support for CMake generators other than Ninja

add_custom_command() calls allow to set up preprocessing of qml files via some external tool, where the tool provides a depfile result as a result of its execution, and thus CMake will know when to rerun the tool in case any of the files in the depfile have been changed.

But depfile support for add_custom_command is only supported for the Ninja generator.

Having the support in Xcode / Makefiles / MSBuild would allow proper dependency tracking in a cross-generator case, and thus making sure builds are rebuilt successfully regardless of the generator that application developer uses.

https://gitlab.kitware.com/cmake/cmake/-/issues/20286