src/vs/workbench/api/common/extHostExtensionActivator.ts/ExtensionsActivator/activateById
class ExtensionsActivator:	public activateById(extensionId: ExtensionIdentifier, reason: ExtensionActivationReason): Promise<void> {
		const desc = this._registry.getExtensionDescription(extensionId);
		if (!desc) {
			throw new Error('Extension `' + extensionId + '` is not known');
		}

		return this._activateExtensions([{
			id: desc.identifier,
			reason
		}]);
	}