feat(slock): implement ext_session_lock_v1 backend

note: did not run lints or fully test yet

src/wayland/session_lock/shell_integration.cpp

@@ -0,0 +1,20 @@
+#include "shell_integration.hpp"
+
+#include <private/qwaylandshellsurface_p.h>
+#include <private/qwaylandwindow_p.h>
+#include <qlogging.h>
+
+#include "session_lock.hpp"
+#include "surface.hpp"
+
+QtWaylandClient::QWaylandShellSurface*
+QSWaylandSessionLockIntegration::createShellSurface(QtWaylandClient::QWaylandWindow* window) {
+	auto* lock = LockWindowExtension::get(window->window());
+	if (lock == nullptr || lock->surface == nullptr || !lock->surface->isExposed()) {
+		qFatal() << "Visibility canary failed. A window with a LockWindowExtension MUST be set to "
+		            "visible via LockWindowExtension::setVisible";
+		throw nullptr;
+	}
+
+	return lock->surface;
+}