Add infrastructure-ui-source to the Assets (elastic#94)

This is an asset which we don't have yet in modules today but could become useful in the future. I'm adding it here for completeness and for having a discussion around it. It is not expected to be supported in our first version.

ASSETS.md

@@ -241,6 +241,17 @@ or support inheritance / composition like the index templates in Elasticsearch.
 problem as a user would have to constantly switch between them. The integrations manager could work around this by
 append / updating index pattern. But this will lead to the problem on how to remove these fields again.
 
+### Infrastructure UI Source
+
+* Asset Path: `kibana/infrastructure-ui-source/*.json`
+
+The Infrastructure UI source is used to tell the Logs and Metrics UI which indices to query for data and how to 
+visualise the data.
+
+The asset is like dashboards / visualizations just a saved object and can be loaded the same way. But the Logs UI 
+could also add an API for a tighter integration. At the moment there is no selection in the UI to change / switch the source
+but it can be triggered through URL parameters.
+
 ### Space
 
 * Asset Path: `kibana/space/*.json`

dev/package-examples/coredns-1.0.1/kibana/infrastructure-ui-source/default.json

@@ -0,0 +1,35 @@
+{
+    "infrastructure-ui-source" : {
+        "name" : "Default",
+        "description" : "",
+        "metricAlias" : "coredns-*",
+        "logAlias" : "coredns-*",
+        "fields" : {
+            "container" : "container.id",
+            "host" : "host.name",
+            "pod" : "kubernetes.pod.uid",
+            "tiebreaker" : "_doc",
+            "timestamp" : "@timestamp"
+        },
+        "logColumns" : [
+            {
+                "timestampColumn" : {
+                    "id" : "5e7f964a-be8a-40d8-88d2-fbcfbdca0e2f"
+                }
+            },
+            {
+                "fieldColumn" : {
+                    "id" : " eb9777a8-fcd3-420e-ba7d-172fff6da7a2",
+                    "field" : "event.dataset"
+                }
+            },
+            {
+                "messageColumn" : {
+                    "id" : "b645d6da-824b-4723-9a2a-e8cece1645c0"
+                }
+            }
+        ]
+    },
+    "type" : "infrastructure-ui-source",
+    "updated_at" : "2019-09-05T09:42:51.592Z"
+}

testdata/package/example-0.0.2/kibana/infrastructure-ui-source/default.json

@@ -0,0 +1,35 @@
+{
+    "infrastructure-ui-source" : {
+        "name" : "Default",
+        "description" : "",
+        "metricAlias" : "example-*",
+        "logAlias" : "example-*",
+        "fields" : {
+            "container" : "container.id",
+            "host" : "host.name",
+            "pod" : "kubernetes.pod.uid",
+            "tiebreaker" : "_doc",
+            "timestamp" : "@timestamp"
+        },
+        "logColumns" : [
+            {
+                "timestampColumn" : {
+                    "id" : "5e7f964a-be8a-40d8-88d2-fbcfbdca0e2f"
+                }
+            },
+            {
+                "fieldColumn" : {
+                    "id" : " eb9777a8-fcd3-420e-ba7d-172fff6da7a2",
+                    "field" : "event.dataset"
+                }
+            },
+            {
+                "messageColumn" : {
+                    "id" : "b645d6da-824b-4723-9a2a-e8cece1645c0"
+                }
+            }
+        ]
+    },
+    "type" : "infrastructure-ui-source",
+    "updated_at" : "2019-09-05T09:42:51.592Z"
+}