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/pvr/texture_loader_pvr.cpp

@@ -169,9 +169,11 @@ RES ResourceFormatPVR::load(const String &p_path, const String &p_original_path,
 void ResourceFormatPVR::get_recognized_extensions(List<String> *p_extensions) const {
 	p_extensions->push_back("pvr");
 }
+
 bool ResourceFormatPVR::handles_type(const String &p_type) const {
 	return ClassDB::is_parent_class(p_type, "Texture2D");
 }
+
 String ResourceFormatPVR::get_resource_type(const String &p_path) const {
 	if (p_path.get_extension().to_lower() == "pvr")
 		return "Texture2D";