Is your feature request related to a problem? Please describe.

Creating a feature to populate development datastore using a JSON or a YAML file. This feature will help shorten the beam job testing time, since developers will be able to do comprehensive testing of their beam job locally.

Describe the solution (or solutions) you'd like

This is an expected developer workflow:

1. go to datastore admin page on local server
2. clicks a button to "populate datastore using JSON" or "populate datastore using YAML"
3. a modal open asking for the text input
4. user fills the text area in the modal like

    "model1": [
        {
            "field1": "val1",
            "field2": "val2",
            "field3": "val3"
        },
        {
            "field1": "val1",
            "field2": "val2",
            "field3": "val3"
        }
    ],
    "model2": [
        {
            "field1": "val1",
            "field2": "val2",
            "field3": "val3"
        }
    ]
}

OR

  - field1: val1
    field2: val2
    field3: val3
  - field1: val1
    field2: val2
    field3: val3
model2:
  - field1: val1
    field2: val2
    field3: val3

5. then clicks populate button.
6. now the 2 instances of model1 and 1 instance of model2 should be in the datastore.

Describe alternatives you've considered and rejected

N/A

Additional context

N/A