Kernel: Close unix domain socket when it gets destoyed

Inode closing is something that needs a complete rework. Currently all
sockets are closed when close() is called, which leads to connection
closing if you fork()/exec() with socket being marked as CLOEXEC.

Inodes should probably only be closed once they are not referenced
anywhere.

kernel/include/kernel/Networking/UNIX/Socket.h

@@ -33,6 +33,7 @@ namespace Kernel
 
 	private:
 		UnixDomainSocket(SocketType, ino_t, const TmpInodeInfo&);
+		~UnixDomainSocket() { on_close_impl(); }
 
 		BAN::ErrorOr<void> add_packet(BAN::ConstByteSpan);