Core functionality of connect and make_request methods on Backend class

[AlexVelezLl]

Summary

Description of the change(s) you made

Implements the core funcitonlity and error handling of the connect and make_request methods on the Backend class.

Manual verification steps performed

Created various sub-classes of the Backend class testing its connect and make_requests methods.

---

Reviewer guidance

How can a reviewer test these changes?

Play with the Backend class, making sub-classes in the test_base.py file

References

Closes #4447

---

Contributor's Checklist

PR process:

• If this is an important user-facing change, PR or related issue the CHANGELOG label been added to this PR. Note: items with this label will be added to the CHANGELOG at a later time
• If this includes an internal dependency change, a link to the diff is provided
• The docs label has been added if this introduces a change that needs to be updated in the user docs?
• If any Python requirements have changed, the updated requirements.txt files also included in this PR
• Opportunities for using Google Analytics here are noted
• Migrations are safe for a large db

Studio-specifc:

• All user-facing strings are translated properly
• The notranslate class been added to elements that shouldn't be translated by Google Chrome's automatic translation feature (e.g. icons, user-generated text)
• All UI components are LTR and RTL compliant
• Views are organized into pages, components, and layouts directories as described in the docs
• Users' storage used is recalculated properly on any changes to main tree files
• If there new ways this uses user data that needs to be factored into our Privacy Policy, it has been noted.

Testing:

• Code is clean and well-commented
• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical user journeys are covered by Gherkin stories
• Any new interactions have been added to the QA Sheet
• Critical and brittle code paths are covered by unit tests

---

Reviewer's Checklist

This section is for reviewers to fill out.

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[bjester]

For the most part, it looks great! Mostly some small things. The most important things that could use attention are:

1. the issue with url_prefix="", *args, **kwargs
2. exception logging
3. retry behavior
4. repeat calls to __init__

[rtibbles]

I have merged #4499 so rebasing this PR on the current search-recommendations branch should fix the build issue that was observed here!

[bjester]

Looking great! Sorry for the late followup. I responded to your question about the timeouts.

[AlexVelezLl]

Thank you @bjester!! Just added the timeout to the backend request 👐.

[bjester]

Revisiting this I caught more things. Sorry for the back and forth. I think this will be the last before approval.

[AlexVelezLl]

Thank you @bjester! I have addressed the comments 👐.

[bjester]

Nice work!