feat(state): add ifdefs to determine whether input manager is enabled

The relevant input manager code is now wrapped in ifdefs to only run
if the Unity Input Manager is enabled and therefore will provide a
warning if the code is run when it is not enabled.

Author: thestonefox

Runtime/SharedResources/Scripts/UnityInputManagerAxis1DAction.cs

@@ -47,7 +47,11 @@ public float Multiplier
         /// <inheritdoc />
         public void Process()
         {
+#if ENABLE_LEGACY_INPUT_MANAGER
             Receive(Input.GetAxis(AxisName) * Multiplier);
+#else
+            Debug.LogWarning("The Legacy Unity Input Manager is disabled in the player settings.");
+#endif
         }
     }
 }

Runtime/SharedResources/Scripts/UnityInputManagerAxis2DAction.cs

@@ -81,7 +81,11 @@ public float YMultiplier
         /// <inheritdoc />
         public void Process()
         {
+#if ENABLE_LEGACY_INPUT_MANAGER
             Receive(new Vector2(Input.GetAxis(XAxisName) * XMultiplier, Input.GetAxis(YAxisName) * YMultiplier));
+#else
+            Debug.LogWarning("The Legacy Unity Input Manager is disabled in the player settings.");
+#endif
         }
     }
 }

Runtime/SharedResources/Scripts/UnityInputManagerButtonAction.cs

@@ -30,7 +30,11 @@ public KeyCode KeyCode
         /// <inheritdoc />
         public void Process()
         {
+#if ENABLE_LEGACY_INPUT_MANAGER
             Receive(Input.GetKey(KeyCode));
+#else
+            Debug.LogWarning("The Legacy Unity Input Manager is disabled in the player settings.");
+#endif
         }
     }
 }