data workspace extension batch 2 (#12208)

* work in progress

* load projects in view and test cases

* update scope

* make the sql proj menu available in workspace view

* add extension unit test

* address comments

* fix errors

extensions/data-workspace/src/common/projectProviderRegistry.ts

@@ -0,0 +1,45 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { IProjectProvider } from 'dataworkspace';
+import * as vscode from 'vscode';
+import { IProjectProviderRegistry } from './interfaces';
+
+export const ProjectProviderRegistry: IProjectProviderRegistry = new class implements IProjectProviderRegistry {
+	private _providers = new Array<IProjectProvider>();
+	private _providerMapping: { [key: string]: IProjectProvider } = {};
+
+	registerProvider(provider: IProjectProvider): vscode.Disposable {
+		this.validateProvider(provider);
+		this._providers.push(provider);
+		provider.supportedProjectTypes.forEach(projectType => {
+			this._providerMapping[projectType.projectFileExtension.toUpperCase()] = provider;
+		});
+		return new vscode.Disposable(() => {
+			const idx = this._providers.indexOf(provider);
+			if (idx >= 0) {
+				this._providers.splice(idx, 1);
+				provider.supportedProjectTypes.forEach(projectType => {
+					delete this._providerMapping[projectType.projectFileExtension.toUpperCase()];
+				});
+			}
+		});
+	}
+
+	get providers(): IProjectProvider[] {
+		return this._providers.slice(0);
+	}
+
+	clear(): void {
+		this._providers.length = 0;
+	}
+
+	validateProvider(provider: IProjectProvider): void {
+	}
+
+	getProviderByProjectType(projectType: string): IProjectProvider | undefined {
+		return projectType ? this._providerMapping[projectType.toUpperCase()] : undefined;
+	}
+};