feat(frame): rework frame retrieval api (#5527)

Rework the frame api to support working with multiple Frames.
* frameModule.topmost() - now returns the last navigated Frame or
the currently selected tab item's Frame if the tab item's view is a
Frame.
* frameModule.getFrameById(id: string) - returns a navigated Frame by id.
* args.object.page.frame - can be used in page elements event handlers.
Returns the Frame of the current element's page.
* chore: Update madge-android npm script path

tns-core-modules/ui/tab-view/tab-view.android.ts

@@ -11,6 +11,7 @@ import {
 import { textTransformProperty, TextTransform, getTransformedText } from "../text-base";
 import { fromFileOrResource } from "../../image-source";
 import { RESOURCE_PREFIX, ad } from "../../utils/utils";
+import { Frame } from "../frame";
 
 export * from "./tab-view-common";
 
@@ -473,6 +474,12 @@ export class TabView extends TabViewBase {
             }
         });
 
+        const newItem = items[newIndex];
+        const selectedView = newItem && newItem.view;
+        if (selectedView instanceof Frame) {
+            selectedView._pushInFrameStack();
+        }
+
         toLoad.forEach(index => {
             const item = items[index];
             if (this.isLoaded && items[index]) {

tns-core-modules/ui/tab-view/tab-view.ios.ts

@@ -13,6 +13,7 @@ import { Page } from "../page";
 import { profile } from "../../profiling";
 import * as uiUtils from "../utils";
 import * as utils from "../../utils/utils";
+import { Frame } from "../frame";
 
 export * from "./tab-view-common";
 
@@ -253,6 +254,11 @@ export class TabView extends TabViewBase {
 
         const newItem = items[newIndex];
         if (newItem && this.isLoaded) {
+            const selectedView = items[newIndex].view;
+            if (selectedView instanceof Frame) {
+                selectedView._pushInFrameStack();
+            }
+
             newItem.loadView(newItem.view);
         }