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 }]);
	}