Renderer: rewrite render scheduling (#8683)

This rewrites renderer scheduling. Occlusion is now unified in a new Pass type.

src/render/pass/PassElement.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include "../../defines.hpp"
+#include <optional>
+
+class IPassElement {
+  public:
+    virtual ~IPassElement() = default;
+
+    virtual void                draw(const CRegion& damage) = 0;
+    virtual bool                needsLiveBlur()             = 0;
+    virtual bool                needsPrecomputeBlur()       = 0;
+    virtual const char*         passName()                  = 0;
+    virtual void                discard();
+    virtual std::optional<CBox> boundingBox();
+    virtual CRegion             opaqueRegion();
+    virtual bool                disableSimplification();
+};