Use topic name to compute the collection to send the updates in "Standard Solr"

[didiez]

In "Standard Solr" mode, there is no way to route messages dynamically to multiple collections using RegexRouter as noted in the docs.

HttpSolrSinkTask should use topic to send the documents to a solr collection with that very same name. Either appending the collection to the base solrUrl in ... https://github.com/jcustenborder/kafka-connect-solr/blob/c917b5c8e938575b6880729f3dbbb7cac4062cb8/src/main/java/com/github/jcustenborder/kafka/connect/solr/HttpSolrSinkTask.java#L42 Or using the overloaded method process(SolrClient client, String collection) in https://github.com/jcustenborder/kafka-connect-solr/blob/c917b5c8e938575b6880729f3dbbb7cac4062cb8/src/main/java/com/github/jcustenborder/kafka/connect/solr/HttpSolrSinkTask.java#L56