Update AuthorizationsAddedEvent to handle multiple projects

What does this MR do and why?

This MR updates Security::ScanResultPolicies::AddApproversToRulesWorker to handle multiple project_ids to reduce the number of worker jobs when ProjectAuthorization is updated for multiple projects at a time. This change also reduces the number of queries in dispatch? to handle multiple projects together instead of individual projects. We also support project_id to make this change backward compatible. Publish AuthorizationsAddedEvent with multiple ... (!171991 - merged) will update the event publishing logic to publish project_ids instead of project_id.

References

Please include cross links to any resources that are relevant to this MR This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

• https://gitlab.com/gitlab-org/gitlab/-/issues/479316#note_2185282437

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

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

Before	After

How to set up and validate locally

1. Create a group

2. In the group, create a project

3. In the group, go to Policies and create a new scan result policy. Example YAML:

   type: approval_policy
   name: Security
   description: ''
   enabled: true
   policy_scope:
     compliance_frameworks: []
   rules:
     - type: scan_finding
       scanners: []
       vulnerabilities_allowed: 0
       severity_levels: []
       vulnerability_states: []
       branch_type: protected
   actions:
     - type: require_approval
       approvals_required: 1
       user_approvers_ids:
         - 1
         - 4 # User to test with

4. In the project, create an MR (e.g. changing a README)

5. Notice the required approvals

6. Add the user referenced in the policy as a group member with a developer role

7. Verify that the user is added as an approver in the MR to the correct rules (rules where they are referenced as approvers)

Addresses https://gitlab.com/gitlab-org/gitlab/-/issues/479316