Schema Compare extension (#4974)

* extension now working

* fix diff editor title disappearing and remove border from source and target name boxes

* redoing a bunch of stuff that disappeared after rebasing

* add images and add to extensions.ts

* moving a few changes to the right place after rebase

* formatting

* update toolbar svgs

* addressing comments

* add return types

* Adding PR comments

* Adding light and dark theme icons

* Fixing the diff editor title for dark theme

extensions/schema-compare/src/controllers/mainController.ts

@@ -0,0 +1,41 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+'use strict';
+
+import * as azdata from 'azdata';
+import * as vscode from 'vscode';
+import { SchemaCompareDialog } from '../dialogs/schemaCompareDialog';
+
+/**
+ * The main controller class that initializes the extension
+ */
+export default class MainController implements vscode.Disposable {
+	protected _context: vscode.ExtensionContext;
+
+	public constructor(context: vscode.ExtensionContext) {
+		this._context = context;
+	}
+
+	public get extensionContext(): vscode.ExtensionContext {
+		return this._context;
+	}
+
+	public deactivate(): void {
+	}
+
+	public activate(): Promise<boolean> {
+		this.initializeSchemaCompareDialog();
+		return Promise.resolve(true);
+	}
+
+	private initializeSchemaCompareDialog(): void {
+		azdata.tasks.registerTask('schemaCompare.start', (profile: azdata.IConnectionProfile) => new SchemaCompareDialog().openDialog(profile));
+	}
+
+	public dispose(): void {
+		this.deactivate();
+	}
+}