mooclet backend: create magic reward metric and query when creating a mooclet experiment.

[danoswaltCL]

As an experimenter, I don't want to deal with setting up an experiment-specific metric and carefully wiring it up to my mooclet experiment. I want to be able set just the mooclet policy parameters and that will be the only difference between setting up a mooclet experiment vs a native upgrade experiment.

See demo-branch for how I cobbled this together for EASI meeting demo (https://github.com/CarnegieLearningWeb/UpGrade/tree/demo-branch).

https://carnegielearning.slack.com/archives/C08A2LSPM5J/p1738243122240099 for demo and diagrams.

Requirements:

• As an experimenter create my mooclet experiment, when I view the Metrics page, I will see a simple metric and query (percent SUCCESS) set up for me automatically, and I will see the graph in the data tab.

Frontend:

• Would probably be good to put a message on the Metrics tab explaining that we will be creating a special metric and attaching this query after the experiment is created.

Backend:

• On experiment create, if is a Mooclet experiment, we will create a simple metric and attach one query to the experiment automatically so that the user doesn't have to.

• On experiment delete, we should remove this metric.

Implementation details:

1. create a rewardMetricKey with this format: experimentName.toLocaleUpperCase() + '_REWARD';

Note: This needs to be unique because it will be used as a lookup, but this will actually suffice in effect, because Mooclet experiments cannot be created with a name that is not unique (it will 400 in Mooclet server).

2. Save rewardMetricKey to the MoocletExperimentRef, which will mean adding this as a property column in the model. (This will be used later for looking up the experiment during the /log call in separate story.)

3. Create a simple metric with this exact format and save to db.

{
      metric: <rewardMetricKey>,
      datatype: IMetricMetaData.CATEGORICAL,
      allowedValues: [ "SUCCESS", "FAILURE" ]
};

4. Create a query of this metric and attach it to the experiment (before saving the experiment and its queries):

{
        id: uuid(),
        name: "Success Rate",
        query: {
            operationType: "percentage",
            compareFn: "=",
            compareValue: "SUCCESS"
        },
        metric: {
            key: rewardMetricKey
        },
        repeatedMeasure: REPEATED_MEASURE.mostRecent
    }

[zackcl]

Here is the example design of the read-only Mooclet Reward Metric section:

[danoswaltCL]

@zackcl looks good, I created a separate story for the stepper part so it can be worked in parallel #2203