feat(misconf): Support --ignore-policy in config scans

[simar7]

Description

Adds support for passing --ignore-policy to ignore misconfiguration results in misconf scanning. Also correctly displays the exception count.

Before

trivy  config  <input>

main.yaml (cloudformation)

Tests: 12 (SUCCESSES: 3, FAILURES: 9, EXCEPTIONS: 0)
Failures: 9 (UNKNOWN: 0, LOW: 2, MEDIUM: 1, HIGH: 6, CRITICAL: 0)

After

trivy   config --ignore-policy=./config-ignore-policy.rego <input>

main.yaml (cloudformation)

Tests: 12 (SUCCESSES: 3, FAILURES: 8, EXCEPTIONS: 1)
Failures: 8 (UNKNOWN: 0, LOW: 2, MEDIUM: 1, HIGH: 5, CRITICAL: 0)

Related issues

• Close --ignore-policy unavailable in config target #3490

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[nikpivkin]

left a few comments

[simar7]

Looks like k8s tests are failing because of disk issues but we have #5387 in place

[nikpivkin]

lgtm