Fix bugs in streaming code you hit if using more than 1 inventory

[AlanCoding]

Generally, ansible-runner will take a lot of different things from the inventory parameter.

• A dict, which is the outright definition of an inventory
• A list of strings that don't exist as files or folders, being an alternative definition of an inventory
• A list of paths to inventory sources
• A single string that is a path to an inventory source

If you look at what we're doing in several of this places, we obviously abandon support for all but the last of these formats. In containerized jobs, we don't support that either, less the inventory file is named "hosts" in the inventory folder... which may be the same as not providing the parameter in the first place.

This adds just enough support for those other cases to allow me to get it working with a list of inventory files.