Public api changes to namespace accounts & connection. (#2383)

* 1.Added following functions to namespace accounts
function getAllAccounts(): Thenable<AccountWithProviderHandle[]>;
function getSecurityToken(account: AccountWithProviderHandle): Thenable<{}>;
2.Added class AccountWithProviderHandle as the wrapper for Account
3.Changed function openConnectionDialog of namespace connection to allow connection dialog initialized with specified parameters, i.e., server name, database name, etc.
function openConnectionDialog(provider?: string[], initialConnectionProfile?: IConnectionProfile): Thenable<connection.Connection>;

* Added unit tests for ExtHostAccountManagement.$getAllAccounts

src/sql/sqlops.d.ts

@@ -1848,6 +1848,19 @@ declare module 'sqlops' {
 		 * @param {Account} updatedAccount Account object with updated properties
 		 */
 		export function accountUpdated(updatedAccount: Account): void;
+
+		/**
+		 * Gets all added accounts.
+		 * @returns {Thenable<Account>} Promise to return the accounts
+		 */
+		export function getAllAccounts(): Thenable<AccountWithProviderHandle[]>;
+
+		/**
+		 * Generates a security token by asking the account's provider
+		 * @param {Account} account Account to generate security token for
+		 * @return {Thenable<{}>} Promise to return the security token
+		 */
+		export function getSecurityToken(account: AccountWithProviderHandle): Thenable<{}>;
 	}
 
 	/**
@@ -1915,6 +1928,21 @@ declare module 'sqlops' {
 		isStale: boolean;
 	}
 
+	/**
+	 * Represents an account with account provider's handle
+	 */
+	export interface AccountWithProviderHandle {
+		/**
+		 * Account
+		 */
+		account: Account;
+
+		/**
+		 * Account's provider handle
+		 */
+		providerHandle: number;
+	}
+
 	// - ACCOUNT PROVIDER //////////////////////////////////////////////////
 	/**
 	 * Error to be used when the user has cancelled the prompt or refresh methods. When