Dump input policy on failure in debug mode

[gberche-orange]

Is your feature request related to a problem? Please describe.

As a hcunit user

• in order to troubleshoot failed assertion
• I need an easy way to inspect the content of the input object against which policies are executed

Describe the solution you'd like

when --debug flag is set (possibly with an additional --dump-input), then upon a policy failure, then the input structure is dumped to stdout as yaml (which includes all hashes, i.e. rendered templates, values and potential others in the future)

Describe alternatives you've considered

• automatically executing "hcunit render" on failures, see https://github.com/orange-cloudfoundry/osb-to-helm-poc/blob/9e56063ad125fdd94c036d406fba9132861ea678/mysql-charts/test.bash#L10-L50 but this currently blocked by #28

Additional context
Add any other context or screenshots about the feature request here.