If anything happened to call arp functions in the wrong order and called
IRegistrar's Issue function before SetApplicationLaunchProperty, we'd
read from an uninitialized ApplicationLaunchProperty instance.
Instead, we can always initialize it so if this does happen, then the
outcome of doing such a thing is at least consistently reproducible.
Resolves numerous deprecation warnings throughout the codebase due to
inclusion of this header. Now building core should be significantly less
noisy (and also relying on less global state).
This also uncovered quite a few modules that were relying on indirect
includes, which have also been fixed.
