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.

core/io/multiplayer_api.cpp

@@ -179,6 +179,7 @@ void _profile_node_data(const String &p_what, ObjectID p_id) {
 		EngineDebugger::profiler_add_frame_data("multiplayer", values);
 	}
 }
+
 void _profile_bandwidth_data(const String &p_inout, int p_size) {
 	if (EngineDebugger::is_profiling("multiplayer")) {
 		Array values;
@@ -668,6 +669,7 @@ Error MultiplayerAPI::_encode_and_compress_variant(const Variant &p_variant, uin
 
 	return OK;
 }
+
 Error MultiplayerAPI::_decode_and_decompress_variant(Variant &r_variant, const uint8_t *p_buffer, int p_len, int *r_len) {
 	const uint8_t *buf = p_buffer;
 	int len = p_len;