XWIKI-19006: Add helpers to manipulate custom parameters in SimpleEventQuery

...iki/eventstream/query/AbstractPropertyQueryCondition.java

...va/org/xwiki/eventstream/query/CompareQueryCondition.java

...in/java/org/xwiki/eventstream/query/InQueryCondition.java

...in/java/org/xwiki/eventstream/query/SimpleEventQuery.java

.../java/org/xwiki/eventstream/query/SortableEventQuery.java

...test/java/org/xwiki/eventstream/SimpleEventQueryTest.java

...xwiki/eventstream/store/solr/internal/SolrEventStore.java

...xwiki/eventstream/store/solr/internal/EventStoreTest.java

...lr-api/src/main/java/org/xwiki/search/solr/SolrUtils.java

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