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/array.cpp

@@ -83,9 +83,11 @@ const Variant &Array::operator[](int p_idx) const {
 int Array::size() const {
 	return _p->array.size();
 }
+
 bool Array::empty() const {
 	return _p->array.empty();
 }
+
 void Array::clear() {
 	_p->array.clear();
 }
@@ -151,6 +153,7 @@ void Array::_assign(const Array &p_array) {
 void Array::operator=(const Array &p_array) {
 	_assign(p_array);
 }
+
 void Array::push_back(const Variant &p_value) {
 	ERR_FAIL_COND(!_p->typed.validate(p_value, "push_back"));
 	_p->array.push_back(p_value);
@@ -509,6 +512,7 @@ Array::Array() {
 	_p = memnew(ArrayPrivate);
 	_p->refcount.init();
 }
+
 Array::~Array() {
 	_unref();
 }