Issue #3303882 by mkalkbrenner: Add configuration option to not index some languages

config/schema/search_api_solr.schema.yml

search_api_solr.install

search_api_solr.module

src/Controller/SolrFieldTypeListBuilder.php

src/Plugin/search_api/backend/SearchApiSolrBackend.php

src/Utility/Utility.php

...est/config/install/search_api.index.solr_search_index.yml

...nfig/install/search_api.index.solr_search_index_cloud.yml

...olr_test/config/install/search_api.index.techproducts.yml

tests/src/Kernel/UtilitiesTest.php