Improve regex used for segregating date criteria
Improve regex used for segregating date criteria

Rather than only treating fields that end in `_date` as a date field,
match any field with `date` in it, either at the edge of the word or
surrounded by underscores, eg:

- date_of_occurrence
- opened_date
- some_date_thing

gds-attic/finder-api,gds-attic/finder-api