Feature/add json report

[mat1e]

New endpoint to get the report as Json for a repository.
It is available from /system/api on the UI.

Example :

Curl
curl -X GET "http://localhost:8081/service/rest/v1/report/json/maven-releases" -H "accept: application/json"

Response code
200

Response headers

 content-length: 735  content-type: application/json  date: Wed, 30 Sep 2020 23:21:09 GMT  server: Nexus/3.24.0-02 (OSS)  x-content-type-options: nosniff 

Response body

[
  {
    "group": "org.sonatype.nexus.plugins",
    "name": "nexus-report-plugin",
    "version": "0.1.2",
    "format": "maven2",
    "size": 3686343,
    "sizeMB": 3.52,
    "sizeGB": 0,
    "createdBy": "admin",
    "lastUpdated": "2020-10-01T01:17:52",
    "lastDownloaded": "never",
    "encoded": "bWF2ZW4tcmVsZWFzZXM6ODg0OTFjZDFkMTg1ZGQxMzYzMjY4ZjIyMGU0NWQ3ZGU"
  },
  {
    "group": "org.sonatype.nexus",
    "name": "nexus-ui-plugin",
    "version": "3.24.0-02",
    "format": "maven2",
    "size": 5494,
    "sizeMB": 0.01,
    "sizeGB": 0,
    "createdBy": "admin",
    "lastUpdated": "2020-10-01T01:20:41",
    "lastDownloaded": "never",
    "encoded": "bWF2ZW4tcmVsZWFzZXM6YzBhYzJhYjZjNWU5M2E0YTc2Zjc5OTEwMjllMDk0Yzg"
  }
]