Add agent and project details in the workspace annotations

MR: Pending

Description

As part of Come up with more user-friendly scheme for rand... (#409774 - closed) • Ashvin Sharma • 18.5, we removed agent id and user id from the workspace name (and by extension the namespace name) in favor of more user friendly names. Since this information is not available in the name anymore, we would like to put it in the annotations to help with debugging issues.

Acceptance criteria

• Add following keys in the annotations
  • workspaces.gitlab.com/agentk_id
  • workspaces.gitlab.com/project_id - this will be optional if we add project-less workspaces
  • workspaces.gitlab.com/namespace_id - this is the GitLab group AKA namespace - we don't call it group_id because in the future we may support also personal namespaces. For now, this would be the id of the group containing the project.

Implementation plan

1. Add annotations in ee/lib/remote_development/workspace_operations/create/desired_config/config_values_extractor.rb
2. Add annotations in all the relevant spec files and fixtures.