Added appContext in Metrics

[RidhamShah]

Completed

• Updated Metric model to add context as an array
• Updated Migration file
• Update CRUD operations
• Added a new API to get metrics only having the given context.
• Updated stepper to show metrics belonging to the context
• Updated test cases for the changes
• Updated format of pre-created metrics from .env file

Remaining

• create a way to add context in the JSON editor of metrics. ( For this part a new issue crated for UI design - ISSUE )

[RidhamShah]

Can we confirm about the new metrics structure of env file
@amurphy-cl @danoswaltCL

METRICS = [
     {
          metrics: [
               {
                    metric: totalTimeSeconds, 
                    datatype: 'continuous'
               },
               {
                    metric: 'workspaceCompletionStatus',
                    ...
               },
               {
                    groupClass: 'addWorkspace',
                    allowedKeys: ['level1', 'level2'],
                    ...
               }
          ],
          contexts: [ context1, context2 ]
     },
     {
          metrics: [ ... ]
          contexts: [ ... ]
     }
]

[zackcl]

@RidhamShah I'm getting the uncaughtException: column "context" of relation "metric" contains null values error when trying this branch. Should I clear my postgres database to make the branch work?

Update: Clearing the postgres DB fixed the error.

[zackcl]

@RidhamShah I've updated the METRICS in the .env file as the one in the .env.example file, but I don't see the pre-created metrics in the UI. Is there something I need to do in order to add the metrics defined in the .env file?

METRICS=[{"metrics":[{"metric":"totalTimeSeconds","datatype":"continuous"},{"groupClass":"masteryWorkspace","allowedKeys":["calculating_area_various_figures","Compare_functions_diff_reps_quadratic"],"attributes":[{"metric":"timeSeconds","datatype":"continuous"}]}],"contexts":["context_identifier_1"]}]

[zackcl]

Nevermind, I saw that you renamed the METRICS to PRE_DEFINED_METRICS in your PR.