Enable optional native login in the inventory ansible role

[mogul]

User Story

In order to enable deployment and testing of inventory CKAN in non-BSP environments, we want the setup of local vs SAML authentication to be configurable with a variable.

Acceptance Criteria

• GIVEN sandbox environments are configured with inventory_ckan_saml2_enabled: false
  WHEN the inventory.yml playbook is run
  THEN the environment is configured with CKAN's native user/password login
• GIVEN that the BSP environments are configured with inventory_ckan_saml2_enabled: true
  WHEN the inventory.yml playbook is run
  THEN the environment is configured with SAML2 authentication

Details

Similar work has already been done for catalog.

Will need to

• Upgrade to correct version of repoze.who library
• Use default who.ini file (don't replace with saml2 version)
• Add variable configuration for CKAN extensions list similar to current catalog implementation

[adborden]

Added some AC.

[adborden]

Was just chatting with @jbrown-xentity @pjsharpe07, we probably don't want to do this work, at least not as described. We can pull in a few similar changes from 1c86878 and 71b64e9, but we don't actually need to combine saml2 into the inventory role. We should be able to just skip the role based on the inventory_app_saml2_enabled variable.

In the longer-term, #1473 will address the tech debt and remove the need for the saml2 role.

I'm going to rename this issue so it's more clear as to what we're after.