Request #67101 SolrDisMaxQuery::addBoostQueryField

Add support to set bq argument through SolrDisMaxQuery
Method Signature:
proto SolrDisMaxQuery SolrDisMaxQuery::addBoostQueryField(string field, string value [, float boost])
outputs bq=field:value^boost
Fixes Bug #68179 Argument list parameter - Argument to value separator disappears sometimes

Fixed various issues with argument separator disappearance