clang-tidy: partially fix hicpp-explicit-conversions

src/include/containers/List.hpp

@@ -101,7 +101,7 @@ public:
 
 	struct Iterator {
 		T node;
-		Iterator(T v) : node(v) {}
+		explicit Iterator(T v) : node(v) {}
 
 		operator T() const { return node; }
 		operator T &() { return node; }

src/modules/ekf2/ekf2_main.cpp

@@ -97,7 +97,7 @@ extern "C" __EXPORT int ekf2_main(int argc, char *argv[]);
 class Ekf2 final : public ModuleBase<Ekf2>, public ModuleParams, public px4::WorkItem
 {
 public:
-	Ekf2(bool replay_mode = false);
+	explicit Ekf2(bool replay_mode = false);
 	~Ekf2() override;
 
 	/** @see ModuleBase */

src/modules/sensors/sensors.cpp

@@ -114,7 +114,7 @@ extern "C" __EXPORT int sensors_main(int argc, char *argv[]);
 class Sensors : public ModuleBase<Sensors>, public ModuleParams
 {
 public:
-	Sensors(bool hil_enabled);
+	explicit Sensors(bool hil_enabled);
 	~Sensors() override;
 
 	/** @see ModuleBase */