Add option to disable SNOMED expression processing from queries if it's not configured

[ppazos]

The query builder / edit should not show the in_snomed_ed operator if the SNOMED expression processing is disabled.

We can add a config area where individual config items can be set, like flags with type and value. We have something like that somewhere.

[ppazos]

• a flag was added to the ConfigurationItems
• a check for the flag was added on the query execution in DataCriteria.toSQL()
• TODO: don't add the in_snomed operator if the snquery is disabled