Show variable usage count on variable tab

lib/variables/variable-usage.hpp

@@ -0,0 +1,15 @@
+#pragma once
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+namespace advss {
+
+struct VariableUsage {
+	int referenceCount = 0;
+	std::vector<std::string> macroNames;
+};
+
+std::unordered_map<std::string, VariableUsage> GetVariableUsage();
+
+} // namespace advss