Update date filter for syscheck endpoints

[davidjiglesias]

|Related issue| |#4466|

Description

This PR fixes date filter for q parameter in syscheck endpoints. It adds the option to use "%Y-%m-%d" format apart from timestamp and "%Y-%m-%d %H:%M:%S"

Tests

Added 3 mocha tests:

Syscheck
    GET/syscheck/:agent_id
(node:2286) Warning: Setting the NODE_TLS_REJECT_UNAUTHORIZED environment variable to '0' makes TLS connections and HTTPS requests insecure by disabling certificate verification.
      ✓ Request (359ms)
      ✓ Pagination (252ms)
      ✓ Retrieve all elements with limit=0 (252ms)
      ✓ Sort (251ms)
      ✓ Search (252ms)
      ✓ Params: Bad agent id (77ms)
      ✓ Errors: No agent (235ms)
      ✓ Filters: Invalid filter (80ms)
      ✓ Filters: Invalid filter - Extra field (78ms)
      ✓ Filters: file (255ms)
      ✓ Filters: type (243ms)
      ✓ Filters: summary (244ms)
      ✓ Filters: md5 (258ms)
      ✓ Filters: sha1 (254ms)
      ✓ Filters: sha256 (254ms)
      ✓ Filters: hash (255ms)
      ✓ Filters: distinct (258ms)
      ✓ Filters: "%Y-%m-%d" date (312ms)
      ✓ Filters: "%Y-%m-%d %H:%M:%S" date (314ms)
      ✓ Filters: timestamp date (314ms)
    GET/syscheck/:agent_id/last_scan
      ✓ Request (256ms)
      ✓ Params: Bad agent id (80ms)
      ✓ Errors: No agent (236ms)
    DELETE/syscheck/:agent_id
      ✓ Request (243ms)
      ✓ Params: Bad agent id (78ms)
      ✓ Errors: No agent (240ms)
    DELETE/experimental/syscheck
      ✓ Request (571ms)
    PUT/syscheck/:agent_id
      ✓ Request (257ms)
      ✓ Params: Bad agent id (82ms)
      ✓ Errors: No agent (254ms)
    PUT/syscheck
      ✓ Request (260ms)

  31 passing (7s)