[ACA-3394] Generally available file preview feature for extensions (#1496)

* Adding general purpose preview overlay route

Preparation for file preview feature

Remove unnecessary preview root route and ability to use loadChildren

Extract RouterExtensionService

Remove loadChildren support and use component instead

Cover RouterExtensionService with unit tests

Fix tests

Fix build

Fix rebase issue

Add generally available PluginPreviewAction

Add data option to child routes and navigateBackAsClose option for the preview component

Support plain mode preview

Fix linting

Update to latest alpha of ADF

* Adding documentation

* Rebase fix

* Update to latest adf

docs/extending/routes.md

@@ -18,6 +18,18 @@ To create a new route, populate the `routes` section with the corresponding entr
       "path": "ext/bin",
       "layout": "app.layout.main",
       "component": "your.component.id",
+      "children": [
+        {
+          "id": "plugin1.routes.bin.preview",
+          "path": "preview/:nodeId",
+          "component": "app.components.preview",
+          "data": {
+              "navigateBackAsClose": true,
+              "simplestMode": true
+          },
+          "outlet": "viewer"
+        }
+      ],
       "parentRoute": "your-parent-route"
     }
   ]
@@ -34,7 +46,8 @@ To create a new route, populate the `routes` section with the corresponding entr
 | layout        | The layout [component](/extending/components) to use for the route.                              |
 | auth          | List of [authentication guards](#authentication-guards). Defaults to `[ "app.auth" ]`. |
 | data          | Custom property bag to carry with the route.                                           |
-| parentRoute   | The path that the route will become child of                                           |
+| children      | List of child routes of the injected route. [More info](#dynamically-injected-routes-with-their-children) |
+| parentRoute   | The path that the route will become child of. See more info about and its limitations under the [Child routes](#child-routes) section |
 
 Use the `app.layout.main` value for the `layout` property to get the default application layout,
 with header, navigation sidebar and main content area.
@@ -72,6 +85,8 @@ Defaults to the `['app.auth']` value.
 
 ## Child Routes
 
+### Injecting child routes under top-level routes: `parentRoute`
+
 Extensions may register a routes that are children of some existing application routes.
 Imagine the situation when application has the following route structure:
 
@@ -109,6 +124,18 @@ so giving you an option for nested linking: `/files/my-path`.
 
 > For the time being, you can provide child entries only for the root (top-level) routes.
 
+### Dynamically injected routes with their children
+
+For a dynamically created route, we can define the children property as well, which contain the child routes of the mainly injected route. For the time being, for a child route, the following properties are supported and translated to Angular's Router configuration:
+
+| Property      | Description                                       |
+| -             | -                                                 |
+| **id**        | Unique identifier.                                |
+| **path**      | Runtime path of the route.                        |
+| **component** | The main [component](/extending/components) to use for the route. |
+| data          | Custom property bag to carry with the route. |
+| outlet        | Router outlet's name. Especially useful when using the PluginPreviewAction within a plugin |
+
 ## Authentication Guards
 
 Below is the list of the authentication guards main application registers on startup.