feat: Implement ObjectTag retrieve REST API

[yusuf-musleh]

Description

This PR implements the tagging REST API for retrieving object tags.

Adding/updating object tags will be handled in a subsequent PR.

Supporting Information

• Closes [Tagging] Implement tagging REST API: Retrieve object tags modular-learning#81

Testing instructions

• Ensure that the tests cover the expected behavior of the view as described in the related issue.

---

Private-ref: FAL-3452

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[pomegranited]

Thank you @yusuf-musleh , this is looking good.

I've requested one small change below, but once that's done it's good to go into CC review.
@bradenmacdonald could you have a look when you get a chance?

👍

• I tested this by running the edx-platform code from open-craft/openedx-platform#577 with this branch installed. Created some object_tags using the shell, and checked that the REST API returned the expected data when queried.
• I read through the code
• I checked for accessibility issues N/A
• Includes documentation for the added REST API

[bradenmacdonald]

Looks good. I just had one request about adding a test case, but you can also let me know if it's already covered somewhere else.

[pomegranited]

@yusuf-musleh Could you also please bump the patch version ? see openedx_learning/init.py

[yusuf-musleh]

@yusuf-musleh Could you also please bump the patch version ? see openedx_learning/init.py

Yup! Just updated it.

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