AudioServer: Assorted infrastructure work

* Add a LibAudio, and move WAV file parsing there (via AWavFile and AWavLoader)
* Add CLocalSocket, and CSocket::connect() variant for local address types.
  We make some small use of this in WindowServer (as that's where we
  modelled it from), but don't get too invasive as this PR is already
  quite large, and the WS I/O is a bit carefully done
* Add an AClientConnection which will eventually be used to talk to
  AudioServer (and make use of it in Piano, though right now it really
  doesn't do anything except connect, using our new CLocalSocket...)

Libraries/LibCore/CLocalSocket.cpp

@@ -0,0 +1,19 @@
+#include <LibCore/CLocalSocket.h>
+#include <sys/socket.h>
+
+CLocalSocket::CLocalSocket(CObject* parent)
+    : CSocket(CSocket::Type::Local, parent)
+{
+    int fd = socket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
+    if (fd < 0) {
+        set_error(fd);
+    } else {
+        set_fd(fd);
+        set_mode(CIODevice::ReadWrite);
+        set_error(0);
+    }
+}
+
+CLocalSocket::~CLocalSocket()
+{
+}