feat: added enterprise theming changes (#139)

[subhashree-sahu31]

• feat: added enterprise theming changes

• fix: fixed newline breaking changes

• fix: removed the whitespace

(cherry picked from commit a681c1f)

Description
This PR backports edx/edx-platform PR #139 to openedx/openedx-platform:master.

It adds enterprise theming support to the AuthN MFE context so enterprise learners can receive enterprise-specific branding data during login and registration flows.

Changes included in this backport:

Adds enterprise branding fields to the AuthN MFE context serializer
Extends AuthN MFE context generation to include enterprise branding details when the request is associated with an enterprise customer
Adds enterprise support helpers for retrieving branding configuration
Makes enterprise branding metadata available for downstream login/registration experiences

Impacted user roles:

Learner: affected, because enterprise learners may now see enterprise-specific branding in authentication flows
Developer: affected, because AuthN MFE context and enterprise helper behavior now include additional branding data
Operator: affected, because enterprise branding behavior depends on enterprise configuration being available and correct
Implications for consumers of this change:

Enterprise learners can receive a more branded authentication experience
Non-enterprise users should remain unaffected
Any frontend consuming the AuthN MFE context can use the new enterprise branding payload when present
Enterprise branding data availability now depends on enterprise customer resolution and branding configuration responses

Supporting information
Original PR: [https://github.com/edx/pull/139]

Original commit: a681c1f

This is a backport from edx/edx-platform/release-ulmo into openedx/openedx-platform:master.

[openedx-webhooks]

Thanks for the pull request, @subhashree-sahu31!

This repository is currently maintained by @openedx/wg-maintenance-openedx-platform-oncall.

Once you've gone through the following steps feel free to tag them in a comment and let them know that your changes are ready for engineering review.

🔘 Get product approval

If you haven't already, check this list to see if your contribution needs to go through the product review process.

• If it does, you'll need to submit a product proposal for your contribution, and have it reviewed by the Product Working Group.
  • This process (including the steps you'll need to take) is documented here.
• If it doesn't, simply proceed with the next step.

🔘 Provide context

To help your reviewers and other members of the community understand the purpose and larger context of your changes, feel free to add as much of the following information to the PR description as you can:

• Dependencies

  This PR must be merged before / after / at the same time as ...

• Blockers

  This PR is waiting for OEP-1234 to be accepted.

• Timeline information

  This PR must be merged by XX date because ...

• Partner information

  This is for a course on edx.org.

• Supporting documentation
• Relevant Open edX discussion forum threads

🔘 Submit a signed contributor agreement (CLA)

⚠️ We ask all contributors to the Open edX project to submit a signed contributor agreement or indicate their institutional affiliation.
Please see the CONTRIBUTING file for more information.

If you've signed an agreement in the past, you may need to re-sign.
See The New Home of the Open edX Codebase for details.

Once you've signed the CLA, please allow 1 business day for it to be processed.
After this time, you can re-run the CLA check by adding a comment below that you have signed it.
If the CLA check continues to fail, you can tag the @openedx/cla-problems team in a comment for further assistance.

🔘 Get a green build

If one or more checks are failing, continue working on your changes until this is no longer the case and your build turns green.

Details

---

Where can I find more information?

If you'd like to get more details on all aspects of the review process for open source pull requests (OSPRs), check out the following resources:

• Overview of Review Process for Community Contributions
• Pull Request Status Guide
• Making changes to your pull request

When can I expect my changes to be merged?

Our goal is to get community contributions seen and reviewed as efficiently as possible.

However, the amount of time that it takes to review and merge a PR can vary significantly based on factors such as:

• The size and impact of the changes that it introduces
• The need for product review
• Maintenance status of the parent repository

💡 As a result it may take up to several weeks or months to complete a review and merge your PR.