Add env var for socket timeout

src/constants.ts

@@ -32,4 +32,4 @@ export enum CompressionMethod {
 // Socket timeout in milliseconds during download.  If no traffic is received
 // over the socket during this period, the socket is destroyed and the download
 // is aborted.
-export const SocketTimeout = 5000;
+export const DefaultSocketTimeout = 5000;