Move the Default{...}LayerFactory into a new web/default_factory.js file

This patch, first of all, removes circular dependencies in the TypeScript definitions. Secondly, it also moves `RenderingStates` into `web/ui_utils.js` to break another type-dependency and directly use the `XfaLayerBuilder` during XFA-printing.
Finally, note that this patch *slightly* reduces the size of the default viewer (e.g. in the `MOZCENTRAL` build) by not having to bundle code which is completely unused.

web/ui_utils.js

@@ -25,6 +25,13 @@ const VERTICAL_PADDING = 5;
 
 const LOADINGBAR_END_OFFSET_VAR = "--loadingBar-end-offset";
 
+const RenderingStates = {
+  INITIAL: 0,
+  RUNNING: 1,
+  PAUSED: 2,
+  FINISHED: 3,
+};
+
 const PresentationModeState = {
   UNKNOWN: 0,
   NORMAL: 1,
@@ -832,6 +839,7 @@ export {
   PresentationModeState,
   ProgressBar,
   RendererType,
+  RenderingStates,
   roundToDivide,
   SCROLLBAR_PADDING,
   scrollIntoView,