RFE: Make molecule collection aware

[cidrblock]

As a user I want molecule to be aware that my scenarios are contained within an ansible collection.

Use cases:

• Use the collection name when constructing the ephemeral directory. Today, if using molecule in multiple collections the ephemeral directory is shared due to the introduction of the "extensions" directory.

/home/bthornto/.cache/molecule
└── extensions
    ├── default
    │   └── inventory

• Provide the collection name to the user for use in ansible content, e.g. molecule_collection_name. This may be used in task names, debugging, etc and will avaoid the need for every user to parse the galaxy.yml file
• Will allow for the introduction of shared resources between scenarios within the same collection. See follow up RFEs