update the json schema and tests with file contents section

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

internal/presenter/poweruser/json_presenter_test.go

@@ -125,6 +125,9 @@ func TestJSONPresenter(t *testing.T) {
 				},
 			},
 		},
+		FileContents: map[source.Location]string{
+			source.NewLocation("/a/place/a"): "the-contents",
+		},
 		Distro: &distro.Distro{
 			Type:       distro.RedHat,
 			RawVersion: "7",

internal/presenter/poweruser/test-fixtures/snapshot/TestJSONPresenter.golden

@@ -1,4 +1,12 @@
 {
+ "fileContents": [
+  {
+   "location": {
+    "path": "/a/place/a"
+   },
+   "contents": "the-contents"
+  }
+ ],
  "fileMetadata": [
   {
    "location": {
@@ -198,6 +206,14 @@
      "scope": ""
     }
    },
+   "contents": {
+    "cataloger": {
+     "enabled": false,
+     "scope": ""
+    },
+    "skip-files-above-size": 0,
+    "globs": null
+   },
    "secrets": {
     "cataloger": {
      "enabled": false,