Move primitive wrappers into its own package "imgui.type"

imgui-lwjgl3/src/test/java/ExampleUi.java

@@ -1,7 +1,7 @@
-import imgui.ImBool;
+import imgui.type.ImBool;
 import imgui.ImColor;
 import imgui.ImGui;
-import imgui.ImString;
+import imgui.type.ImString;
 import imgui.ImVec2;
 import imgui.flag.ImGuiColorEditFlags;
 import imgui.flag.ImGuiCond;