Update cs_scanimage.py to perform assessment on policy, instead of score.

[atul-bhardwaj-sp]

Please provide an option to pass or fail based on policy and the ability to pass a specific policy name/id to the script for assessment.. The cs_scanimage.py script is currently passing or failing based on score but we would like to use policies for assessment. We prefer policy over score for several reasons.

• Score is an arbitrary value that may not reflect the desired results.
• Multiple policies can be configured and applied on disparate subsets of our code.
• To provide Crowdstrike functionality to the appropriate stakeholders in the company we would like the CI/CD team to manage invocation of the image scan but would like the CISO org to manage the policy applied to the scans.

It's a priority 2 for us.