build/lib/policies.ts/queryVersions
async function queryVersions(serviceUrl: string, languageId: string): Promise<Version[]> {
	const res = await fetch(`${serviceUrl}/extensionquery`, {
		method: 'POST',
		headers: {
			'Accept': 'application/json;api-version=3.0-preview.1',
			'Content-Type': 'application/json',
			'User-Agent': 'VS Code Build',
		},
		body: JSON.stringify({
			filters: [{ criteria: [{ filterType: 7, value: `ms-ceintl.vscode-language-pack-${languageId}` }] }],
			flags: 0x1
		})
	});

	if (res.status !== 200) {
		throw new Error(`[${res.status}] Error querying for extension: ${languageId}`);
	}

	const result = await res.json() as { results: [{ extensions: { versions: { version: string }[] }[] }] };
	return result.results[0].extensions[0].versions.map(v => parseVersion(v.version)).sort(compareVersions);
}