Fix #100485: Alembic export crash with names containing a forward slash

As Alembic stores hierarchies as paths separated by a forward slash, such
character cannot be used in a name. This resulted in an uncaught thrown
exception. To fix this, replace '/' with '_' like for other illegal
characters.

source/blender/io/alembic/exporter/abc_hierarchy_iterator.cc

@@ -84,6 +84,7 @@ std::string ABCHierarchyIterator::make_valid_name(const std::string &name) const
   std::replace(abc_name.begin(), abc_name.end(), ' ', '_');
   std::replace(abc_name.begin(), abc_name.end(), '.', '_');
   std::replace(abc_name.begin(), abc_name.end(), ':', '_');
+  std::replace(abc_name.begin(), abc_name.end(), '/', '_');
   return abc_name;
 }