src/vs/platform/userDataSync/common/userDataSyncBackupStoreService.ts/UserDataSyncBackupStoreService/backup
class UserDataSyncBackupStoreService:	async backup(resourceKey: SyncResource, content: string): Promise<void> {
		const folder = joinPath(this.environmentService.userDataSyncHome, resourceKey);
		const resource = joinPath(folder, `${toLocalISOString(new Date()).replace(/-|:|\.\d+Z$/g, '')}.json`);
		try {
			await this.fileService.writeFile(resource, VSBuffer.fromString(content));
		} catch (e) {
			this.logService.error(e);
		}
		try {
			this.cleanUpBackup(resourceKey);
		} catch (e) { /* Ignore */ }
	}