Fix IPC on Forge 1.17.1 - 1.20.1 (#4187)

* Reapply "Implement a more robust IPC system between the launcher and client (#4159)"

This reverts commit e25d726da4.

* Put game JAR and theseus JAR ahead of other JARs in classpath

* Fix 1.17-1.20 Forge by forcefully removing Multi-Release manifest entry

* Fix formatting

---------

Co-authored-by: Prospector <6166773+Prospector@users.noreply.github.com>

packages/app-lib/src/util/network.rs

@@ -0,0 +1,17 @@
+use std::io;
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
+use tokio::net::TcpListener;
+
+pub async fn tcp_listen_any_loopback() -> io::Result<TcpListener> {
+    // IPv4 is tried first for the best compatibility and performance with most systems.
+    // IPv6 is also tried in case IPv4 is not available. Resolving "localhost" is avoided
+    // to prevent failures deriving from improper name resolution setup. Any available
+    // ephemeral port is used to prevent conflicts with other services. This is all as per
+    // RFC 8252's recommendations
+    const ANY_LOOPBACK_SOCKET: &[SocketAddr] = &[
+        SocketAddr::new(IpAddr::V4(Ipv4Addr::LOCALHOST), 0),
+        SocketAddr::new(IpAddr::V6(Ipv6Addr::LOCALHOST), 0),
+    ];
+
+    TcpListener::bind(ANY_LOOPBACK_SOCKET).await
+}