Add errors into detailed policy bot comment

What does this MR do and why?

This MR adds policy evaluation errors into detailed policy bot comment.

Depends on !147561 (merged).

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Missing artifacts (CI misconfiguration)	Scan removed	Recording
		CleanShot_2024-03-25_at_18.48.35

How to set up and validate locally

1. Create a project
2. Enable feature flag in rails console:

   Feature.enable(:save_policy_violation_data, Project.last)

3. Go to Secure -> Policies and create a new Merge request approval policy with the following YAML:

   type: approval_policy
   name: Sec & Lic
   description: ''
   enabled: true
   rules:
     - type: scan_finding
       scanners: []
       vulnerabilities_allowed: 0
       severity_levels: []
       vulnerability_states: []
       branch_type: protected
     - type: license_finding
       match_on_inclusion: true
       license_types:
         - BSD 3-Clause "New" or "Revised" License
       license_states:
         - newly_detected
       branch_type: protected
   actions:
     - type: require_approval
       approvals_required: 1
       role_approvers:
         - developer

4. Configure with merge request & merge
5. Go back to the project and update README.md in a new MR
6. Verify that bot comment is created and includes two errors, mentioning missing artifacts.

Related to #433403 (closed)