records: allow submitters to preview bidirectional links

[GraemeWatt]

Information specified by the related_to_table_dois and related_to_hepdata_records fields is not currently rendered when a record is in preparation and has not yet been finalised, probably because of the changes made in PR #732 to improve the linking of records/tables for records with multiple versions. This makes it difficult for submitters to know if they have specified these fields correctly, leading to situations like https://www.hepdata.net/record/ins2729396?version=1 where duplicate links appear because the bidirectional links have been specified both ways in the encoding. The following changes should be made:

• The related_to_table_dois links in the forward direction should always be shown irrespective of whether the two related records are in preparation or finalised.
• The related_to_table_dois links in the backward direction should be shown if the records containing the referring tables have been finalised or if the referring tables are in the same record (which might not be finalised).
• The related_to_hepdata_records links in the forward direction should always be shown irrespective of whether the two related records are in preparation or finalised.
• The related_to_hepdata_records links in the backward direction should only be shown if the most recent versions of the referring records have been finalised.

Could you please look into these issues, @ItIsJordan?

[GraemeWatt]

Closed by PR #805.