Implement correct ordering of self-referential local-only indexes

[pospi]

This issue currently only affects EconomicResource.contains and manifests as nondeterministic return order of contained resources.

It should be resolved as part of #337 and will definitely go away once we move to an integrity zome architecture in #264; but deserves its own issue as there are some additional DHT storage bloat optimisations that might need to be made in addressing it. In short, since hdk_semantic_indexes_zome_lib::sync_index does not currently create time indexes for the destination link targets, and these are triggered separately in hdk_records::identity_helpers::create_entry_identity, you don't actually get bidirectional time indexes created unless you manually request that both sides of an index be created. This breaks for self-referential indexes, since only 1 RPC call is made to update them (both sides being in the same zome means this is sufficient for updating the semantic indexing components of the link structure).