XWIKI-17162: Create new needed Solr core at runtime

.gitignore

...atform-search-solr/xwiki-platform-search-solr-api/pom.xml

...ain/java/org/xwiki/search/solr/internal/AbstractSolr.java

.../xwiki/search/solr/internal/DefaultSolrConfiguration.java

...ain/java/org/xwiki/search/solr/internal/EmbeddedSolr.java

.../main/java/org/xwiki/search/solr/internal/RemoteSolr.java

...va/org/xwiki/search/solr/internal/SolrClientInstance.java

...org/xwiki/search/solr/internal/api/SolrConfiguration.java

...c/main/resources/solr/defaultcore/conf/managed-schema.xml

...i/src/main/resources/solr/defaultcore/conf/solrconfig.xml

.../java/org/xwiki/search/solr/internal/DefaultSolrTest.java

.../search/solr/internal/EmbeddedSolrInitializationTest.java

...orm-search-solr/xwiki-platform-search-solr-server/pom.xml

...olr-server/xwiki-platform-search-solr-server-data/pom.xml

...guration-resources/src/main/resources/xwiki.properties.vm