Add filtering by deliverer

Use `paraphrase` gem to simplify query logic.

Add constants in `DeliveryQuery` to map keywords to query param values.
This avoids hard-coding query param values throughout the codebase and
allows changing the values with minimal code churn or breaking
functionality.

Switch sorting feature test to use desk worker names to assert order
since the `appear_before` matcher finds 'UPS' and 'LaserShip' in the
`<select>` first. It isn't possible to limit the assertion to a part of
the page with `within` since the orderly gem uses `page.body` to make
the assertion[1].

[1] https://github.com/jmondo/orderly/blob/master/lib/orderly.rb#L8
Only re-render delivery search results, not entire page

Previously, the header content displaying the selected date and the
next/previous day links would need to be re-rendered when switching
days. Using a form, this isn't the case.
Move delivery search URL update to route
Basic styling for delivery search filters