Changes to Select one contract by closest delta (no full-chain download)

added the optional property detail/items/ctx to the response with the 422 status

added the optional property detail/items/input to the response with the 422 status

added the non-success response with the status 500

added the optional property meta/stale_since to the response with the 200 status

added the optional property meta/data_age_days to the response with the 200 status

added the optional property meta/notes to the response with the 200 status

added the optional property meta/period to the response with the 200 status

endpoint added