Add AWS secret retrieval for ArgoCD

[lgallard]

What?

This PR updates the Terraform configuration to retrieve the Argo Cd Server Admin Password from AWS Secrets Manager and use it in the Helm deployment of Argo CD.

Why?

To enhance security by managing sensitive passwords through AWS Secrets Manager, ensuring centralized secret management and adherence to best practices.

[github-actions[bot]]

💰 Infracost report

Monthly cost will not change

Cost details (includes details of unsupported resources and skipped projects due to errors)

``` ────────────────────────────────── 131 projects have no cost estimate changes. Run the following command to see their breakdown: infracost breakdown --path=/path/to/code ────────────────────────────────── 2338 cloud resources were detected: ∙ 615 were estimated ∙ 1607 were free ∙ 116 are not supported yet, see https://infracost.io/requested-resources: ∙ 42 x aws_identitystore_group_membership ∙ 23 x aws_identitystore_user ∙ 10 x aws_guardduty_member ∙ 8 x aws_ssoadmin_permission_set ∙ 7 x aws_identitystore_group ∙ 5 x aws_fms_policy ∙ 5 x aws_s3_bucket_lifecycle_configuration ∙ 4 x aws_guardduty_detector ∙ 2 x aws_guardduty_organization_admin_account ∙ 2 x aws_guardduty_organization_configuration ∙ 2 x aws_organizations_delegated_administrator ∙ 1 x aws_eks_access_entry ∙ 1 x aws_fms_admin_account ∙ 1 x aws_organizations_organization ∙ 1 x aws_route53_resolver_firewall_domain_list ∙ 1 x aws_route53_resolver_firewall_rule ∙ 1 x aws_route53_resolver_firewall_rule_group ```

_{This comment will be updated when code changes.}