fullMesh.stl fails for proofreading annotations for unchanged agglomerates

[fm3]

segmentIdsForAgglomerateIdIfNeeded uses the mappingName which is set to the editable mapping id, but notices that the proofreading doesn’t have the agglomerate id.

fallback uses the agglomerate file, but the filename is wrong, since that would have to use the base mapping name.

The base mapping name should be sent along the editable mapping tracing id.

This means that the logic of segmentIdsForAgglomerateIdIfNeeded must be restructured to still accomodate all cases. (current logic wouldn’t even check for editableMappingTracingId if a matching mappingName is set.)