[fenix] Move experimenter.json to experimenter.yaml

.experimenter.yaml

@@ -23,9 +23,18 @@ messaging:
     actions:
       type: json
       description: A growable map of action URLs.
+    message-under-experiment:
+      type: string
+      description: Id or prefix of the message under experiment.
     messages:
       type: json
       description: A growable collection of messages
+    on-control:
+      type: string
+      description: What should be displayed when a control message is selected.
+      enum:
+        - show-none
+        - show-next-message
     styles:
       type: json
       description: "A map of styles to configure message appearance.\n"

app/build.gradle

@@ -407,7 +407,7 @@ nimbus {
     // This is generated by the FML and should be checked into git.
     // It will be fetched by Experimenter (the Nimbus experiment website)
     // and used to inform experiment configuration.
-    experimenterManifest = ".experimenter.json"
+    experimenterManifest = ".experimenter.yaml"
 }
 configurations {
     // There's an interaction between Gradle's resolution of dependencies with different types