Dynamic DPI scaling (#1980)

* DPI scaling
 1. Add the ability to query the operating system's DPI scaling values
 2. Expose those values through a new Lua function
 3. Add an asset that sets the CEF gui and the Dashboard font sizes and placements based on the DPI scaling
 4. Add that new asset into the base_blank asset
* Add message when including the dpiscaling

include/openspace/engine/windowdelegate.h

@@ -64,6 +64,8 @@ struct WindowDelegate {
 
     glm::vec2 (*dpiScaling)() = []() { return glm::vec2(1.f); };
 
+    float (*osDpiScaling)() = []() { return 1.f; };
+
     bool (*hasGuiWindow)() = []() { return false; };
 
     bool (*isGuiWindow)() = []() { return false; };