adds JSON/Py file loaders

[Omanshb]

The following change adds JSON and Python Script File loaders to EvaDB.

[github-actions]

👋 Hello @Omanshb, thanks for submitting a EVA DB PR 🙏 To allow your work to be integrated as seamlessly as possible, we advise you to:

• ✅ Verify that your PR is up-to-date with georgia-tech-db/eva master branch. If your PR is behind you can update your code by clicking the 'Update branch' button or by running git pull and git merge master locally.
• ✅ Verify that all EVA DB Continuous Integration (CI) checks are passing.
• ✅ Reduce changes to the absolute minimum required for your bug fix or feature addition.

[xzdandy]

Hi @Omanshb, thanks for add json and py file support. Is PR ready? Could you add some testcases and documentations? Thanks!

[hershd23]

Is this up for review?

[jarulraj]

FAILED test/integration_tests/long/test_model_train.py::ModelTrainTests::test_xgboost_regression - evadb.executor.executor_utils.ExecutorError: 'EvaDBDatabase' object has no attribute 'config' -- @jineetd any idea?