[EASI-3919] - Notification settings

[patrickseguraoddball]

EASI-3919

Changes and Description

• Added route for notifications setting
• Added query and mutation for fetching and saving
• Added form components
• Error state
• LD Flag around route
• Unit tests

taggedInDiscussionReply is not currently being rendered in the UI, but it's data should always match taggedInDiscussion for now.

How to test this change

• Navigate to /notifications/settings
• Verify all in-app notifications are always disabled
• Verify form persists
• Verify that taggedInDiscussionReply data always mirrors taggedInDiscussion when fetching/updating

PR Author Review Checklist

• Met the ticket's acceptance criteria, or will meet them in a subsequent PR.
• Added or updated tests for backend resolvers or other functions as needed.
• Added or updated client tests for new components, parent components, functions, or e2e tests as necessary.
• Updated the Postman Collection if necessary.

PR Reviewer Guidelines

• It's best to pull the branch locally and test it, rather than just looking at the code online!
• Check that all code is adequately covered by tests - if it isn't feel free to suggest the addition of tests.
• Always make comments, even if it's minor, or if you don't understand why something was done.

[garyjzhao]

Looks GRRReat!