Add local env runtime variables override for local testing

[yuli-han]

Summary

Currently Chronon set the runtime environment variables from several sources based on the below priority order:
- Environment variables existing already.
- Environment variables derived from args (like app_name)
- conf.metaData.modeToEnvMap for the mode (set on config)
- team environment per context and mode set on teams.json
- default team environment per context and mode set on teams.json
- Common Environment set in teams.json

The team environment per context mode set is a team level environment setting which defined in the json file teams.json. Team could put the environment settings(like EMR clusters and queue) based on their need, and these settings will be applied to all the jobs within the team folder.

However, sometimes our users may want to test their new job locally, the local tests may use different environment settings comparing with the prod run on airflow. Currently they need to add their job config into a different folder(like the test folder) other than the production folder(which will be parsed as context), and add context specific environment variables, but this may bring new complexity to the testing process since they still have to copy their changes to the production config to make it work in production environment.

This PR is trying to solve this problem by introducing a new arg env whose default value is dev. Users can define runtime environment variables for different environment in teams.json file, for example, for production environment and dev environment:

"production": {
    "backfill": {
        "EMR_CLUSTER": "backfill-shared-prod",
        "EMR_QUEUE": "backfill"
    },
    "upload": {
        "EMR_CLUSTER": "backfill-shared-prod",
        "EMR_QUEUE": "backfill"
    }
},
"dev": {
    "backfill": {
        "EMR_CLUSTER": "homes-shared-prod-ap",
        "EMR_QUEUE": "staging"
    }
},

1. For production run on airflow, the job will be scheduled with --env=production, so the production environment will be used.
2. For local testing, the default env is dev, so if the dev environment is provided in teams.json file, dev environment will be used, otherwise production environment will be used.

Why / Goal

Test Plan

• Added Unit Tests
• Covered by existing CI
• Integration tested

1. dev environment is provided in teams.json, env=production
   Local tests with
   python3 scripts/run.py --mode=backfill --conf=production/joins/zipline_test/test_online_join_small.v2 --ds=2024-02-20 --env=production

2. dev environment is provided in teams.json, env=dev
   Local tests with
   python3 scripts/run.py --mode=backfill --conf=production/joins/zipline_test/test_online_join_small.v2 --ds=2024-02-20 --env=dev

3. dev environment is provided in teams.json, env is not used
   Local tests with
   python3 scripts/run.py --mode=backfill --conf=production/joins/zipline_test/test_online_join_small.v2 --ds=2024-02-20

4. dev environment is not provided in teams.json, env = dev
   Local tests with
   python3 scripts/run.py --mode=backfill --conf=production/joins/zipline_test/test_online_join_small.v2 --ds=2024-02-20 --env=dev

Checklist

• Documentation update

Reviewers

@better365

[pengyu-hou]

[nikhilsimha]

Minor comments. Congrats on your first chronon PR Yuli!