Use the pkg/cache in Source-Controller

[souleb]

A cache package has been developed to cache objects with an objective to provide a better performance and reduce stress on cloud providers APIs.

The following list the tasks to be done in Source-Controller in order to achieve the aforementioned objective:

• [ ] cache contextual-login credentials for OCI artifacts; https://github.com/fluxcd/source-controller/pull/1521
• [ ] Replace the cache used for Helm indexes
• [ ] The clients used in pkg/azure|gcp|minio should be reused, they are thread safe and can handle token refresh