Add yaml validation for scan result policies

What does this MR do and why?

Describe in detail what your merge request does and why.

Add yaml validation for scan result policies

• gernalize current yaml validation
• update tests

Changelog: changed

EE: true

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Policy Type	Screenshot
project scan execution
group scan execution
project scan result
group scan result
non existent

No validation example shown with the following below patch

diff --git a/ee/app/assets/javascripts/security_orchestration/components/utils.js b/ee/app/assets/javascripts/security_orchestration/components/utils.js
index ad2255bd3f4c..1f6a055f0d13 100644
--- a/ee/app/assets/javascripts/security_orchestration/components/utils.js
+++ b/ee/app/assets/javascripts/security_orchestration/components/utils.js
@@ -44,7 +44,7 @@ export const getSinglePolicySchema = async ({ namespacePath, namespaceType, poli
           description: 'Specifies the type of policy to be enforced.',
           enum: policyType,
         },
-        ...schemaForMultiplePolicies.properties[policyType].items.properties,
+        ...schemaForMultiplePolicies.properties['a'].items.properties,
       },
     };
   } catch {

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Navigate to a project => Security & Compliance => Policies => New policy => Scan Result policy => yaml mode (example gdk url)
2. Verify yaml validation
3. Navigate to a project => Security & Compliance => Policies => New policy => Scan Execution policy => yaml mode (example gdk url)
4. Verify yaml validation
5. Navigate to a group => Security & Compliance => Policies => New policy => Scan Result policy => yaml mode (example gdk url)
6. Verify yaml validation
7. Navigate to a group => Security & Compliance => Policies => New policy => Scan Execution policy => yaml mode (example gdk url)
8. Verify yaml validation

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #393435 (closed)