[GST]Ensure GST initialized before playing with GST Quirks

https://bugs.webkit.org/show_bug.cgi?id=303326

Reviewed by NOBODY (OOPS!).

GStreamerQuirksManager verifies each quirk with isPlatformSupported()
that usually relies on gst elements presense in the registry.
Calling this without gst_init called fails for every gst element and
rejects all quirks.

The problem exists for apps that don't use any of canPlayType() or
isTypeSupported() that handle gst_init internally.

* Source/WebCore/platform/gstreamer/GStreamerQuirks.cpp:
(WebCore::GStreamerQuirksManager::GStreamerQuirksManager):

Original author: Andrzej Surdej <[email protected]>
See: WebPlatformForEmbedded/WPEWebKit#1584

Author: vivienne-w

Source/WebCore/platform/gstreamer/GStreamerQuirks.cpp

@@ -63,6 +63,7 @@ GStreamerQuirksManager::GStreamerQuirksManager(bool isForTesting, bool loadQuirk
 {
     static std::once_flag debugRegisteredFlag;
     std::call_once(debugRegisteredFlag, [] {
+        ensureGStreamerInitialized();
         GST_DEBUG_CATEGORY_INIT(webkit_quirks_debug, "webkitquirks", 0, "WebKit Quirks");
     });