Improve term search from OBO homepage

[jamesaoverton]

Discussed on the 2020-07-14 Operations call:

1. Make term search more prominent: There's a search box in the upper right that I managed to forget entirely. Consensus on the call was to make this more prominent, probably by moving it directly above the ontology table.

2. Term search more portals: Current term search is for all of Ontobee. It would be nice to add OLS, Bioportal, and maybe AberOWL, which are all available from the individual ontology pages.

3. Limit term search to OBO: Current term search is for all of Ontobee, which include non-OBO resources. In the short term, we could explicitly specify all the OBO ontologies in the term search request (likewise for OLS; Bioportal already provides an OBO-only option I think). Longer term, we should ask the browsers if they could each support an OBO-only option. We know that they already slurp our metadata, so their system know which projects are OBO and which are not.

[nlharris]

search definitely has room for improvement, but not clear that anyone has time to take this on.

[nlharris]

See also #2602