Parsing of text queries is currently performed as part of query execution stage building in StageBuilder::build(). This is a problem because StageBuilder::build() is not expected to fail.

This problem should be addressed by moving text query parsing to its natural home, TextMatchExpression::init(). Unfortunately, parsing text queries requires access to the collection's default language; thus, TextMatchExpression needs to be given access to a OperationContext that it can use to determine the default language. To accomplish this, a new argument should be added the MatchExpressionParser constructor of type MatchExpressionParser::TextCallback, which wraps an OperationContext* and exposes a public method parseText() (see the definition of MatchExpressionParser::WhereCallback, which exposes a similar mechanism).