Port the Azure Resource Explorer extension to core. (#2701)

* Port the Azure Resource Explorer extension to core.

This will enable Azure viewlet by default in the next release.

- Moving this code from the SQL Server 2019 extension to Azure Data Studio core
- Ported tests and verified they work in the integration tests.sh file
- Fixed an issue that caused integration tests to fail if you have a SQL Server 2019 big data cluster endpoint listed, but the extension isn't installed.

extensions/azurecore/src/test/index.ts

@@ -0,0 +1,30 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+const path = require('path');
+const testRunner = require('vscode/lib/testrunner');
+
+const suite = 'Integration Azure Tests';
+
+const options: any = {
+	ui: 'bdd',
+	useColors: true,
+	timeout: 60000
+};
+
+if (process.env.BUILD_ARTIFACTSTAGINGDIRECTORY) {
+	options.reporter = 'mocha-multi-reporters';
+	options.reporterOptions = {
+		reporterEnabled: 'spec, mocha-junit-reporter',
+		mochaJunitReporterReporterOptions: {
+			testsuitesTitle: `${suite} ${process.platform}`,
+			mochaFile: path.join(process.env.BUILD_ARTIFACTSTAGINGDIRECTORY, `test-results/${process.platform}-${suite.toLowerCase().replace(/[^\w]/g, '-')}-results.xml`)
+		}
+	};
+}
+
+testRunner.configure(options);
+
+export = testRunner;