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

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

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

@@ -2,6 +2,8 @@
 pub mod fetch;
 pub mod io;
 pub mod jre;
+pub mod network;
 pub mod platform;
 pub mod protocol_version;
+pub mod rpc;
 pub mod server_ping;