Style: Enforce separation line between function definitions

I couldn't find a tool that enforces it, so I went the manual route:
```
find -name "thirdparty" -prune \
  -o -name "*.cpp" -o -name "*.h" -o -name "*.m" -o -name "*.mm" \
  -o -name "*.glsl" > files
perl -0777 -pi -e 's/\n}\n([^#])/\n}\n\n\1/g' $(cat files)
misc/scripts/fix_style.sh -c
```

This adds a newline after all `}` on the first column, unless they
are followed by `#` (typically `#endif`). This leads to having lots
of places with two lines between function/class definitions, but
clang-format then fixes it as we enforce max one line of separation.

This doesn't fix potential occurrences of function definitions which
are indented (e.g. for a helper class defined in a .cpp), but it's
better than nothing. Also can't be made to run easily on CI/hooks so
we'll have to be careful with new code.

Part of #33027.

modules/enet/networked_multiplayer_enet.cpp

@@ -36,6 +36,7 @@
 void NetworkedMultiplayerENet::set_transfer_mode(TransferMode p_mode) {
 	transfer_mode = p_mode;
 }
+
 NetworkedMultiplayerPeer::TransferMode NetworkedMultiplayerENet::get_transfer_mode() const {
 	return transfer_mode;
 }
@@ -113,6 +114,7 @@ Error NetworkedMultiplayerENet::create_server(int p_port, int p_max_clients, int
 	connection_status = CONNECTION_CONNECTED;
 	return OK;
 }
+
 Error NetworkedMultiplayerENet::create_client(const String &p_address, int p_port, int p_in_bandwidth, int p_out_bandwidth, int p_client_port) {
 	ERR_FAIL_COND_V_MSG(active, ERR_ALREADY_IN_USE, "The multiplayer instance is already active.");
 	ERR_FAIL_COND_V_MSG(p_port < 0 || p_port > 65535, ERR_INVALID_PARAMETER, "The server port number must be set between 0 and 65535 (inclusive).");