Allow Vault Credentials for Inventories sources to process encrypted vault files

1. What is the nature and description of the request?

A customer has requested to open a request to allow  Inventories sourced to support vault credentials.

     2. Why does the customer need this? 

Customer wants to AAP better support for vault keys in their inventories sources.

    3. How would you like to achieve this?

Allow the support of the addition of vault credentials to the inventories sources, currently there is no option to add a vault credential. 

    4. Github Link if any

https://github.com/ansible/awx/issues/4089