BLI: Add assert for indexed_data_equal

Typically, we use this function to determine whether or not a subset of
data that has been collected with `gather` needs to be then persisted
into a larger array with `scatter`. As such, it makes sense to assert on
equality of the indices and smaller array size.

Pull Request: https://projects.blender.org/blender/blender/pulls/140752

source/blender/blenlib/BLI_array_utils.hh

@@ -326,6 +326,7 @@ template<typename T> inline void fill_index_range(MutableSpan<T> span, const T s
 template<typename T>
 bool indexed_data_equal(const Span<T> all_values, const Span<int> indices, const Span<T> values)
 {
+  BLI_assert(indices.size() == values.size());
   for (const int i : indices.index_range()) {
     if (all_values[indices[i]] != values[i]) {
       return false;