Add back Azure Resource Explorer extension with updated build script (#2805)

* Revert "Revert "Port the Azure Resource Explorer extension to core." (#2770)"

This reverts commit 210447cd37.

* WIP1

* Add custom build task for azurecore extension

* Fix azurecore output path for macOS build

* Fix linux gulp task name

extensions/azurecore/src/azureResource/interfaces.ts

@@ -0,0 +1,54 @@
+/*---------------------------------------------------------------------------------------------
+ *  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 { ServiceClientCredentials } from 'ms-rest';
+import { Account, DidChangeAccountsParams } from 'sqlops';
+import { Event } from 'vscode';
+
+import { AzureResourceSubscription, AzureResourceDatabaseServer, AzureResourceDatabase } from './models';
+
+export interface IAzureResourceAccountService {
+	getAccounts(): Promise<Account[]>;
+
+	readonly onDidChangeAccounts: Event<DidChangeAccountsParams>;
+}
+
+export interface IAzureResourceCredentialService {
+	getCredentials(account: Account): Promise<ServiceClientCredentials[]>;
+}
+
+export interface IAzureResourceSubscriptionService {
+	getSubscriptions(account: Account, credentials: ServiceClientCredentials[]): Promise<AzureResourceSubscription[]>;
+}
+
+export interface IAzureResourceSubscriptionFilterService {
+	getSelectedSubscriptions(account: Account): Promise<AzureResourceSubscription[]>;
+
+	saveSelectedSubscriptions(account: Account, selectedSubscriptions: AzureResourceSubscription[]): Promise<void>;
+}
+
+export interface IAzureResourceDatabaseServerService {
+	getDatabaseServers(subscription: AzureResourceSubscription, credentials: ServiceClientCredentials[]): Promise<AzureResourceDatabaseServer[]>;
+}
+
+export interface IAzureResourceDatabaseService {
+	getDatabases(subscription: AzureResourceSubscription, credentials: ServiceClientCredentials[]): Promise<AzureResourceDatabase[]>;
+}
+
+export interface IAzureResourceCacheService {
+	get<T>(key: string): T | undefined;
+
+	update<T>(key: string, value: T): void;
+}
+
+export interface IAzureResourceContextService {
+	getAbsolutePath(relativePath: string): string;
+
+	executeCommand(commandId: string, ...args: any[]): void;
+
+	showErrorMessage(errorMessage: string): void;
+}