Restore bgee homology files

[cmungall]

We used to include a TSV of all anatomical homologies. This is useful for users and also for us (e.g. to coordinate with Bgee if we plan to obsolete a term that may be in the table)

This used to be available from http://bgee.unil.ch/download/organ_association.txt

But isn't there any more. There is now a nice UI for querying homology - we added a link in #1501 - but getting access to the raw TSV would be useful for us cc @fbastian

(for historic context, we used to have the homology relationships integrated into the release but we decided this was better as annotation data)

[github-actions[bot]]

This issue has not seen any activity in the past 6 months; it will be closed automatically one year from now if no action is taken.

[fbastian]

We're getting back at this, notably to annotate cell type homology, we'll update you once our pipeline is reactived. This will go through https://github.com/BgeeDB/anatomical-similarity-annotations