Add where command to new query pipeline (siglens#1762)

* Make PEG give "where" command block

* Fix issue passing QueryAggregators

* Add util to remove elements from a slice

* Add IQR method to discard certain rows

* Implement "where" logic

* Add comment

pkg/ast/pipesearch/searchQueryParser.go

@@ -427,6 +427,10 @@ func SearchQueryToASTnode(node *ast.Node, boolNode *ASTNode, qid uint64, forceCa
 }
 
 func searchPipeCommandsToASTnode(node *QueryAggregators, qid uint64) (*QueryAggregators, error) {
+	if config.IsNewQueryPipelineEnabled() {
+		return node, nil
+	}
+
 	var err error
 	var pipeCommands *QueryAggregators
 	//todo return array of queryaggs