As we now have an enum Operator that comes with many useful helper methods switching to use
that instead of the enums defined separately. Also switches to using the new enum's helper
methods where applicable removing duplicate parsing logic.
This breaks backwards compatibility. Documenting the break in
migrate_query_refactoring.asciidoc
Relates to #10217
Moving the query building functionality from the parser to the builders
new toQuery() method analogous to other recent query refactorings. In
this case this also includes FQueryFilterParser, since both queries are
closely related.
Relates to #10217Closes#11729