feat: adds backoff to enterprise-catalog client calls

[brobro10000]

Adds backoff decorator to the enterprise access api client functions as a means to retry calls that may face connection or timeout errors.

I opted for a conservative amount of retries (3) given the exponential nature of the wait_gen or backoff strategy and contains_content_items usage in the can-redeem function.

Description:
Add a description of your changes here.

Jira:
ENT-XXXX

Merge checklist:

• ./manage.py makemigrations has been run
  • Note: This must be run if you modified any models.
    • It may or may not make a migration depending on exactly what you modified, but it should still be run.

Post merge:

• Ensure that your changes went out to the stage instance
• Deploy to prod instance

[adamstankiewicz]

Seems reasonable to me, but I might also defer to a review from someone (e.g.,. Troy?) more familiar with best practices around implementation of this backoff strategy.