Solr 9

[alastair]

Description

Adds a new solr 9 core and removes the old solr 4 core

The new PointInteger field in solr doesn't support being used as
a unique id field, so we switched id to a string. This requires
casting it back to an int in a few places when using it to retrieve
sounds from the database

date fields can be a DatePoint or DateRange, the Range type is used
for filtering within a range (e.g. created:[from TO to]), but the
point field must be used for ordering, so we add the created field
with both types and choose one depending on what we want to do.

Still some experiments to be done on the search results and similarity types that we will use.

Checklist:

• fix tests that use hardcoded solr4.5 backend
• Add test in test_search_engine_backend command for get_user_tags method
• Add test in test_search_engine_backend command for get_pack_tags method
• Update test_search_engine_backend to create a new core for running tests against
• Add test for get_stream_sounds (which also performs a search in solr) and refactor some parts of it if needed
• add a test in test_search_engine_backend scripts to test multiple-word queries.
• Integrate alastair's local solr comparison script into search engine tests (combination of query + filter, including multiple filters and examples with OR on a filter)
• add a test in test_search_engine_backend for geo queries
• Add tests on date facet
• handle difference between datepoint and daterange (created)
• review difference in results on 5 vs 9 based on scoring
• Configure default query operator to be AND instead of OR to replicate the default behaviour of solr < 5
• Move from specific queryhandler to just /select with defaults set
• see if we should use commitAfter instead of always commit
• Use BooleanSimilarity for matches (doesn't include ranking based on number of times a word occurs in the document)
• simplify SolrQuery builder
• Update search documentation to suggest new style of geo search
• Ensure that we're using json for sending and retrieving data from solr