Fix workspaceRoot macro for insights (#4686)

* Fix workspaceRoot macro for insights

The workspaceRoot macro wasn't working correctly for finding the queryFile. There were a couple of issues :

1. The path separators were hardcoded as / which wasn't xplat-compatible
2. They required the first section of the path was one of the folders in the workspace - e.g. if the workspace contained a folder named foo you'd have to specify ${workspaceRoot}\foo\myfile.sql. This is inconsistent with the folder logich was just appends the path after ${workspaceRoot} to the folder that's currently open

I changed the logic to just append the relative part of the path to every folder currently open in the workspace and choose the first one that it found that contained the file we were told to look for - which follows the convention the folder logic uses. If the file doesn't exist it'll just fall back to using the path without the macro (which is likely to not resolve and thus will display an error, but there's nothing we can do at that point anyways)

* Switch to using VS Code resolver (support for more than just workspaceRoot) and move resolution code into helper method so it can be used by the multiple places it's called. Added tests for the methods.

* Add test for invalid param

* Change resolveQueryFilePath to be a standalone exported function. Change it to throw if the file can't be resolved/found so callers can display error correctly. Added more tests to covery new scenarios. Switch to using pfs instead of fs for file existance checks.

* Add extra param to InsightsDialogController construction in test

* Fix formatting and test errors.

* Change to suiteSetup and suiteTeardown so the setup/teardown is only ran once instead of once per test - we don't need unique files and this stops a race condition error with deleting the test folder.

* spaces -> tabs

src/sqltest/stubs/windowTestService.ts

@@ -0,0 +1,19 @@
+/*---------------------------------------------------------------------------------------------
+*  Copyright (c) Microsoft Corporation. All rights reserved.
+*  Licensed under the Source EULA. See License.txt in the project root for license information.
+*--------------------------------------------------------------------------------------------*/
+
+import * as platform from 'vs/base/common/platform';
+import { IWindowConfiguration } from 'vs/platform/windows/common/windows';
+import { TestWindowService as vsTestWindowService } from 'vs/workbench/test/workbenchTestServices';
+
+export class TestWindowService extends vsTestWindowService {
+
+	constructor(private env: platform.IProcessEnvironment) {
+		super();
+	}
+
+	getConfiguration(): IWindowConfiguration {
+		return { userEnv: this.env } as IWindowConfiguration;
+	}
+}