feat: add usage_key for breadcrumbs in search index [FC-0049]

[rpenido]

Description

This PR adds the usage_key for each item in the block breadcrumbs of an index document. This will allow us to have information on the parent to redirect to the right page in the Search Modal.

More Information:

Part of:

• [Course Search] Allow redirect to the unit page from the search results modular-learning#210

Testing Instructions

1. Run your local stack on this branch
2. Make sure you have meilisearch setup locally, follow the setup instructions here https://github.com/open-craft/tutor-contrib-meilisearch, but use the following branch for the plugin (https://github.com/rpenido/tutor-contrib-meilisearch/tree/rpenido/fal-3693-pass-meilisearch-enabled-env-to-mfe-config) to make sure the MEILISEARCH_ENABLED is configured in the MFEs.
3. Run tutor dev run cms bash and ./manage.py cms reindex_studio
4. Access http://meilisearch.local.edly.io:7700/ and check if the created documents have the usage_key field

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Private ref: FAL-3709

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[ChrisChV]

@rpenido Looks good! 👍

• I tested this: I followed the testing instructions
• I read through the code and considered the security, stability and performance implications of the changes.
• Includes tests for bugfixes and/or features added.

[rpenido]

Thank you @ChrisChV!
Could you review/merge this @bradenmacdonald?

[rpenido]

Hi @bradenmacdonald! This is ready for another review

[bradenmacdonald]

Looks good! I'll merge when I can.

[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.