Improve response for site not found case

[BK01]

Current state:
When a site is not found, users receive a 404 and an HTML response regardless of format requested.

Test case:
https://geocoder.api.gov.bc.ca/sites/nearest.json?point=-122.861715%2C49.825979&maxDistance=10

Proposed future state:
When a site not found response is given for a ‘near’ or ‘nearest’ request, a ‘No site found’ response is given in the same format as the request (json, geojson etc) with HTTP 200 status code. In some cases, such as SHP format a different approach may be required.

[BK01]

In the scenario that no site is found -> For all formats provide a response with a status code of 200 in the same format as the request (may be an empty file in some cases).