Add IMS Authentication

[solaris007]

Feature request.

Expected Behaviour

Support authentication by virtue of IMS authentication (pre-existing token or full circle).
Stretch goal: Potentially support resource-specific entitlements.

Actual Behaviour

Only OW credentials are supported.

[meryllblanchet]

Hi, ideally, we would like to see a pluggable authorization mechanism at TVM level, in which we would preserve the default OW credentials validation, but extend by providing an IMS authorization level.

Our management application is multi-tenant and its users should have access to configuration files isolated by IMS org and possible other criteria in the future.

[aiojbot]

JIRA issue created: https://jira.corp.adobe.com/browse/ACNA-1395