daemon: Add support for running as a service on win32

* Minimal implementation of --system on win32.
* Wrap main with a Windows Service on win32 (with a fallback to
  running it directly).
* Update PA_SYSTEM_{RUNTIME,STATE,CONFIG}_PATH and HOME dynamically
  on Windows (overrides the build config, similar to the existing
  config path replacement logic).

Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/549>

src/pulsecore/core-util.h

@@ -310,6 +310,7 @@ bool pa_running_in_vm(void);
 
 #ifdef OS_IS_WIN32
 char *pa_win32_get_toplevel(HANDLE handle);
+char *pa_win32_get_system_appdata();
 #endif
 
 size_t pa_page_size(void);