Add Support for in memory caching

[bmike78]

Prerequisites:

• Is the functionality available in the GitHub UI? If so, please provide a link to information about the feature.
  • technically this is a feature of the safe settings and caching frequently used github API calls

New Feature

• We run a forked copy of safe settings and would like to provide some contributions upstream to be at parity with main-enterprise.

• We run safe settings at a very large scale of several hundred repos today, but technically have it enabled for several thousand repos.

• We are constantly rate limited by the github API and so we've added a simple caching layer, which resulted in about 96-97% of repo contents being cached and got us past our rate limit issues of the endpoint of "/repositories/:repository_id/contents/?"

[bmike78]

@decyjphr, is this something that you would approve of if we issued a PR?

[decyjphr]

Yes, this would be a good addition.

I'll wait for the PR to see the implementation details and will probably have more questions but it will be useful for large orgs.

[DouJohn]

Fyi @decyjphr - I work with Mike at John Deere, and I just opened the linked pr showing how we implemented our cache. Feel free to take a look and tell me what you think