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/animation/animation_blend_space_1d.cpp

@@ -33,6 +33,7 @@
 void AnimationNodeBlendSpace1D::get_parameter_list(List<PropertyInfo> *r_list) const {
 	r_list->push_back(PropertyInfo(Variant::FLOAT, blend_position));
 }
+
 Variant AnimationNodeBlendSpace1D::get_parameter_default_value(const StringName &p_parameter) const {
 	return 0;
 }