IPCCompiler: Use string hashes for IPC endpoint magic

This patch removes the IPC endpoint numbers that needed to be specified
in the IPC files.  Since the string hash is a (hopefully) collision free
number that depends on the name of the endpoint, we now use that
instead. :^)

Userland/Services/AudioServer/AudioClient.ipc

@@ -1,4 +1,4 @@
-endpoint AudioClient = 82
+endpoint AudioClient
 {
     FinishedPlayingBuffer(i32 buffer_id) =|
     MutedStateChanged(bool muted) =|