feat(frontend): Catchup frontend for internal development changes

[cptran777]

This PR catches up various internal changes in order for us to make a PR more dedicated to addressing specific raised issues. It is also an experiment with a new script for streamlining translating internal changes to open source.

Changes include:

• Migration of some modules out of the data-portal host application into its own addons, making it more scalable in the future
• Removal of some internal logics that was leaked into open source
• Updates to change management feature, which allows for email drafting and notification to specific people and groups
• Various minor code clean ups and improvements

Testing done:

Ran docker images and ensured that application still builds and behaves as expected.

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable)