Ref T12819. Supports negating search terms, e.g. "apple -honeycrisp".

When negating a term, we're a little more strict about what can match (that is, what can prevent a document from being returned) since it's easy for a user to type "apple -honeycrisp -honey -crisp -crispies -olcrispers -honeyyums" to keep refining their search, but hard/impossible to split apart an overboard term.

• Ran apple -smith, apple -"granny smith", etc.
• Verified phone -tact does not exclude phone contact.
• (In theory, phone -~tact would, but the parser currently doesn't support this, and I'm not champing at the bit to add support.)