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.

scene/resources/shader.cpp

@@ -159,6 +159,7 @@ Shader::Shader() {
 Shader::~Shader() {
 	RenderingServer::get_singleton()->free(shader);
 }
+
 ////////////
 
 RES ResourceFormatLoaderShader::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, bool p_no_cache) {
@@ -225,6 +226,7 @@ void ResourceFormatSaverShader::get_recognized_extensions(const RES &p_resource,
 		}
 	}
 }
+
 bool ResourceFormatSaverShader::recognize(const RES &p_resource) const {
 	return p_resource->get_class_name() == "Shader"; //only shader, not inherited
 }