57fef57868
In preparation for moving the current code into a new file but retaining the existing dynamic_inventory.py entry-point, this change modifies the main function so that can generate inventory without having to be in the same directory as the env.d dir. An initial attempt to move the `main` function of dynamic_inventory into a structure like this: playbooks/ inventory/ env.d/ <env files> dynamic_inventory.py lib/ generate.py (contents of dynamic_inventory moved here) resulted in errors when trying to access env.d due to using os.path.join(__file__) inside the function. Also, incorporating this change with the move would have resulted in a harder-to-review patch. Instead, the `args` function will be left inside of dynamic_inventory.py when `main` is moved out, so that the CLI-facing code is grouped together. Since the base environment was moved to a command line argument, documentation was added as to its function, as well as the differences from the --config argument. As a side effect, this opens the door to running tests with multiple environment layouts. However, none is added with this review. Change-Id: Ie690f31b64c7381257634a9dbb2ee5b4197fd9bf