feat: include custom relative dates flag info in outline api

[navinkarkera]

Description

Adds custom_relative_dates waffle flag info to course outline rest API. This is required for displaying custom due dates in course outline MFE.

Useful information to include:

• Which edX user roles will this change impact? Developer.

Supporting information

Private-ref: BB-8485

Testing instructions

• Get master devstack up and running.
• Start lms and cms using make {lms,cms}-up.
• Go to http://localhost:18010/api-docs/
• Scroll down till you find documentation for /contentstore/v1/course_index/{course_id} api.
• Use Try it out and check is_custom_relative_dates_active field is included in API.

Deadline

"None" if there's no rush, or provide a specific date or event (and reason) if there is one.

[openedx-webhooks]

Thanks for the pull request, @navinkarkera! Please note that it may take us up to several weeks or months to complete a review and merge your PR.

Feel free to add as much of the following information to the ticket as you can:

• supporting documentation
• Open edX discussion forum threads
• timeline information ("this must be merged by XX date", and why that is)
• partner information ("this is a course on edx.org")
• any other information that can help Product understand the context for the PR

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Please let us know once your PR is ready for our review and all tests are green.

[farhaanbukhsh]

@navinkarkera can I review this as a CC?

[navinkarkera]

@farhaanbukhsh Sure. Thanks!

[openedx-webhooks]

@navinkarkera 🎉 Your pull request was merged! Please take a moment to answer a two question survey so we can improve your experience in the future.

[edx-pipeline-bot]

2U Release Notice: This PR has been deployed to the edX staging environment in preparation for a release to production.

[edx-pipeline-bot]

2U Release Notice: This PR has been deployed to the edX production environment.

[edx-pipeline-bot]

2U Release Notice: This PR has been deployed to the edX production environment.