Feat/model backed ui (#1145)

This is an initial PR for a new model-driven UI where extensions can provide definitions of the components & how they're laid out using Containers.
#1140, #1141, #1142, #1143 and #1144 are all tracking additional work needed to improve the initial implementation and fix some issues with the implementation.

Features:
- Supports defining a FlexContainer that maps to a flexbox-based layout.
- Supports creating a card component, which is a key-value pair based control that will lay out simple information to a user. Eventually this will have an optional set of actions associated with it.
- Has a sample project which shows how to use the API and was used for verification

src/sql/parts/dashboard/widgets/webview/webviewWidget.component.ts

@@ -13,7 +13,7 @@ import { memoize } from 'vs/base/common/decorators';
 
 import { DashboardWidget, IDashboardWidget, WidgetConfig, WIDGET_CONFIG } from 'sql/parts/dashboard/common/dashboardWidget';
 import { DashboardServiceInterface } from 'sql/parts/dashboard/services/dashboardServiceInterface.service';
-import { IDashboardWebview } from 'sql/services/dashboardWebview/common/dashboardWebviewService';
+import { IDashboardWebview } from 'sql/services/dashboard/common/dashboardViewService';
 
 import * as sqlops from 'sqlops';
 
@@ -47,7 +47,7 @@ export class WebviewWidget extends DashboardWidget implements IDashboardWidget,
 	}
 
 	ngOnInit() {
-		this._dashboardService.dashboardWebviewService.registerWebview(this);
+		this._dashboardService.dashboardViewService.registerWebview(this);
 		this._createWebview();
 	}