Names of merged layers are incorrect in variants of component sets

Merged items are usually named following the schemes similar to "parentName_merge" or "parentName_mergeType_mergeCounter", depending on exporter version.

This naming convention seem to be causing issues in Variants of ComponentSets. Each variant has its own name, exporter assigns merged items different ids and it leads to importer being incapable of merging them for proper generation of states property changes.

At the moment we came up with two options for fixes:
1. Introduce special case for ComponentSets - use name of the entire ComponentSet, not a Variant that parents merged items. Instead of "property1_value_merge_mergeCounter" we would get something similar to "componentSetName_merge_mergeCounter". - currently we are following this option
2. Name merged layers based on children names. If user merges 3 items, they would get something like "rectangle1_Vector3_Ellipse_merge_mergeCounter".