CHEF-3961: Implement caching ability at application-level for the API calls

[ahasunos]

Description

This PR introduces application-level caching of the API responses by using the cache manager i.e. ChefLicensing::RestfulClient::CacheManager implemented in this PR.

It maintains a list of the endpoints CACHE_ENDPOINTS in ChefLicensing::RestfulClient::V1 class for which the response needs to be cached at the application level.

Currently, the list contains only the /v1/client endpoint and the list can be extended as required (or the filtering of the endpoints to cache can be removed if we desire to cache for all the endpoints).

The characteristics of the cache manager is as below:

• Library: It extends ActiveSupport::Cache library
• Storage: FileStore storage (defaults to Dir.tmpdir location)
• Expiration Policy: Cache info is received in the body of the API response which contains the expiry timestamp
• Key Naming: The convention is <endpoint_name>_<sorted_license_keys> (Can be made as digest later)

[Other characteristics are yet to be decided]

Related Issue

CHEF-3961: Ability to cache based on per license basis and not at the network level

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (non-breaking change that does not add functionality or fix an issue)

Checklist:

• I have read the CONTRIBUTING document.
• I have run the pre-merge tests locally and they pass.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• All commits have been signed-off for the Developer Certificate of Origin.

[sathish-progress]

I don't see the need to provide an optional cache_dir. Do you have any particular use case? if not I would prefer abstracting it out.

[ahasunos]

I am using the cache_dir during testing.

[sathish-progress]

you can stub it