src/vs/workbench/api/common/extHostWindow.ts/ExtHostWindow/asExternalUri
class ExtHostWindow:	async asExternalUri(uri: URI, options: IOpenUriOptions): Promise<URI> {
		if (isFalsyOrWhitespace(uri.scheme)) {
			return Promise.reject('Invalid scheme - cannot be empty');
		}

		const result = await this._proxy.$asExternalUri(uri, options);
		return URI.from(result);
	}