[Fleet] Add new index to fleet for artifacts being served out of fleet-server

[paul-tavares]

Summary

• Add a new index - .fleet-artifacts - that will store user generated kibana artifacts for download by (initially) Endpoint integration via fleet-server.

Testing Notes:

• you will need to run Fleet with xpack.fleet.agents.fleetServerEnabled: true
• Once running, you can check that the index was created with the expected fields. From the Dev tools in kibana:

GET .fleet-artifacts

Click to see expected Response

{
  ".fleet-artifacts_1" : {
    "aliases" : {
      ".fleet-artifacts" : { }
    },
    "mappings" : {
      "dynamic" : "false",
      "_meta" : {
        "migrationHash" : "e968c1b6e058b7da69f00075d8ffbd49341734cf"
      },
      "properties" : {
        "body" : {
          "type" : "binary"
        },
        "compressionAlgorithm" : {
          "type" : "keyword",
          "index" : false
        },
        "created" : {
          "type" : "date",
          "index" : false
        },
        "decodedSha256" : {
          "type" : "keyword",
          "index" : false
        },
        "decodedSize" : {
          "type" : "long",
          "index" : false
        },
        "encodedSha256" : {
          "type" : "keyword"
        },
        "encodedSize" : {
          "type" : "long",
          "index" : false
        },
        "encryptionAlgorithm" : {
          "type" : "keyword",
          "index" : false
        },
        "identifier" : {
          "type" : "keyword"
        },
        "packageName" : {
          "type" : "keyword"
        },
        "type" : {
          "type" : "keyword"
        }
      }
    },
    "settings" : {
      "index" : {
        "routing" : {
          "allocation" : {
            "include" : {
              "_tier_preference" : "data_content"
            }
          }
        },
        "number_of_shards" : "1",
        "provided_name" : ".fleet-artifacts_1",
        "creation_date" : "1614274012110",
        "number_of_replicas" : "1",
        "uuid" : "a5gQ2zH9QDKS21OIVKTq5A",
        "version" : {
          "created" : "8000099"
        }
      }
    }
  }
}

Closes #92820

Checklist

• Unit or functional tests were updated or added to match the most common scenarios

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[elasticmachine]

Pinging @elastic/security-onboarding-and-lifecycle-mgt (Team:Onboarding and Lifecycle Mgt)

[scunningham]

looks ok to me

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 045e150
• Storybooks Preview

Metrics [docs]

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
fleet	367.6KB	367.6KB	+19.0B

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @paul-tavares

[nchaulet]

🚀