Initial implementation of two-way communication with Fabric host (#1622)

* Listen to iframe messages. Test posting message.

* Plug new container message to show New Container dialog

* Rename message action to type

* Fix format

* Fix format

* Remove console.log() statement

* Rework fabric init flow. Implement open Collection Tab from fabric.

* Rename method to better match its purpose

* Update src/hooks/useKnockoutExplorer.ts

Use connectionString from message

Co-authored-by: Vsevolod Kukol <sevoku@microsoft.com>

* Fix format

* For openTab action open first collection if not specified. Clean up FabricContract.

* Reformat FabricContracts

* Highlight current node selection using them token

* Reformat

* Automatically expand nodes in resource tree if underlying database or collection is expanded. Fix AllowedOrigins. Cleanup code.

* Fix format

* Fix lint issue

* Don't show the home screen for Fabric (#1636)

* Fix formatting

* Database name to open can be overridden by value in session storage

---------

Co-authored-by: Vsevolod Kukol <sevoku@microsoft.com>

src/Contracts/FabricContract.ts

@@ -0,0 +1,25 @@
+export type FabricMessage =
+  | {
+      type: "newContainer";
+      databaseName: string;
+    }
+  | {
+      type: "initialize";
+      connectionString: string | undefined;
+    }
+  | {
+      type: "openTab";
+      databaseName: string;
+      collectionName: string | undefined;
+    };
+
+export type DataExploreMessage =
+  | "ready"
+  | {
+      type: number;
+      data: {
+        action: "LoadDatabases";
+        actionModifier: "success" | "start";
+        defaultExperience: "SQL";
+      };
+    };