Create Solr 8/9 schemas

[tokee]

Currently there are very old (Solr 6?) and just plain old (Solr 7) configurations in the project. As Solr 7 is both EOL and unsuitable for large webarchive-discovery indexes when unpatched, this is problematic.

We should test and upgrade the configurations for Solr 8 and for Solr 9.

[anjackson]

For reference: https://solr.apache.org/guide/solr/latest/upgrade-notes/major-changes-in-solr-9.html

[anjackson]

I experimented with using the Solr API to set up schemas, rather than cloning whole configurations. e.g. these commands called from this script.

In principle, this approach should require less tuning across Solr versions, but I don't think it covers everything we might do with Solr.

[anjackson]

Note also that for Solr 9, to enable SQL we need to set SOLR_MODULES=sql, I think. See modules docs.