Site search: add synonyms

[danicahelb]

see redmine: https://redmine.apidb.org/issues/49818

[danicahelb]

Info from John I:

This task has been complicated by the fact that (as Jie points out) the ontology terms in the database don’t jibe with the files that the ontologies are loaded from. John and I looked into it and found that because of the way we formerly updated ontology records in the database, the workflow undo mechanism was sometimes unable to remove records when we wanted it to. This has been fixed by a subsequent change to the code. The eda-inc instance is still incorrect, but this will be fixed when we install a new instance from scratch for build 63. In the meantime, we can modify site search to use variable-name synonyms as alternative search terms.

I'm moving this task to b63