Show active usage in accounts menu

[RMacfarlane]

When clicking on an account from the accounts menu, there should be an option like "Show Active Usage" that will display a list of features and extensions that have accessed a token for the account during this session

[RMacfarlane]

To verify:

1. Create an extension that uses one of the authentication providers:

		const session = await vscode.authentication.login("github", ['user:email']);
		const token = await session.getAccessToken();
		vscode.window.showInformationMessage(`Successfully logged with ${token}`);

2. After signing in, click on the account in the accounts menu
3. Choose "Show Extensions and Features using this Account", the name of the extension should be displayed

[aeschli]

Verified with steps above