feat: support reading redis config from env vars (optionally with prefix)

[sdewitt-newrelic]

Adds

• Moved DataCache to it's own file
• Don't use noops in DataCache if cache disabled
• Added config class supporting reading config from config file then auto env vars then default
• Updated AuthEnv to use new config class
• Updated integration.py to use new config class
• Updated salesforce.py to use new cache
• Various minor changes