Create violations and bot message for fail-open policies

What does this MR do and why?

This MR changes logic around fail-open policies to persist violations for these cases so that we can highlight skipped policies in the policy bot message. The violations for fail-open policies are created with a different status so that they don't block the MR with policy mergability check.

Changes in this MR:

• Rename violations completed status to failed
• Add warn status
• Refer to failed violations for policy mergability check
• Persist errored, fail-open violations as warn
• Display warn violations in bot comment

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

Fail-closed (current)	Mixed fail-open and fail-closed	Fail-open

How to set up and validate locally

1. Create a project
2. Create a new merge request approval policy:

   type: approval_policy
   name: Scans
   description: ''
   enabled: true
   rules:
     - type: scan_finding
       scanners: []
       vulnerabilities_allowed: 0
       severity_levels: []
       vulnerability_states: []
       branch_type: protected
   actions:
     - type: require_approval
       approvals_required: 1
       role_approvers:
         - developer
     - type: send_bot_message
       enabled: true
   fallback_behavior:
     fail: open

3. Create another merge request approval policy:

   type: approval_policy
   name: Licenses
   description: ''
   enabled: true
   rules:
     - type: license_finding
       match_on_inclusion_license: true
       license_types:
         - MIT License
       license_states:
         - newly_detected
       branch_type: protected
   actions:
     - type: require_approval
       approvals_required: 1
       role_approvers:
         - developer
     - type: send_bot_message
       enabled: true
   fallback_behavior:
     fail: open

4. To verify that bot comment is created when scanner configuration is missing, create a MR by updating README.md
5. Verify that bot comment is created and it contains message: The following policies enforced on your project were skipped because they are configured to fail open: Scans, Licenses.
6. To verify that MR gets blocked with a correct scanner configuration, add .gitlab-ci.yml into the project:

   include:
     - template: Jobs/Dependency-Scanning.gitlab-ci.yml

7. Add empty requirements.txt file
8. Create another MR, adding pytest into requirements.txt
9. Verify that approvals are required and the bot comment contains message: Resolve all violations in the following merge request approval policies: Licenses.

Related to #474853 (closed)