Spike: GA4K: Decrypt data sent by rails to agent along with support for multiple inventory configmap

MR: Add support for decrypting encrypted secrets in... (gitlab-org/cluster-integration/gitlab-agent!1011 - closed)

Description

Spike to make changes proposed in Create workspaces from private repositories (&10882 - closed) on the GA4K codebase.

Acceptance Criteria

• We should be able to create Kubernetes resources with multiple inventory config maps
• We should be able to decrypt data and create Kubernetes Secret from them