Add support for Apache Solr

[alexander-schranz]

One of the wider used search engines beside elasticsearch was always Apache Solr, its also build on top of Apache Lucene. So it is definitly an engine which we would like to support and should give us deeper insights how other engines work.

Todo

• Switch to Cloud mode answer from Reddit
• Create Classes based on other implementations
• Add handling for SchemaManager create, drop and check existing of Indexes (see How to write and read from collections solariumphp/solarium#1049 (reply in thread))
• Create own configset for every collection
• Add handling for SchemaManager with correct field mappings https://www.reddit.com/r/Solr/comments/10kiesz/how_to_create_nested_objects_via_schema_api/
  • Identifier ([Solr] Set uniqueKey to configured value instead of map id #87)
  • Float
  • Int
  • Text
  • Bool
  • Date
  • Object
  • Typed
• Add handling for Connection for save, find, delete documents
• Add handling for text.raw fields for filterable searchable fields
• Add handling for Connection for search by current conditions
  • SearchCondition
  • EqualCondition
  • NotEqualCondition
  • GreaterThanCondition
  • GreaterThanEqualCondition
  • LessThanCondition
  • LessThanEqualCondition
  • LimitAndOffset (still requires SearchCondition to work)
  • SortByAsc
  • SortByDesc