DAP enablement setting

What does this MR do and why?

Adds a setting to enable/disable Duo Agent Platform in admin and group Duo settings page. The presence of this settings is controlled by duo_agent_platform_enabled field passed from the Rails helper. If no duo_agent_platform_enabled field is passed, the setting will be hidden.

References

https://gitlab.com/gitlab-org/gitlab/-/work_items/582878+

Screenshots or screen recordings

duo_agent_platform_enabled field not passed	duo_agent_platform_enabled field passed
not_passed.mov DAP enabled setting is not visible Other DAP-related settings are still visible and can be updated with no issues	passed.mov DAP enabled setting is visible Can only view and update other DAP-related settings when DAP setting is marked as enabled.

How to set up and validate locally

Field not passed:

• Run GDK on non-SAAS mode: GITLAB_SIMULATE_SAAS=0 gdk start
• Go to the GitLab Duo setting page: /admin/gitlab_duo
• Observe:
  • The DAP enabled setting is not visible.
  • Other DAP-related settings (Flows, Foundational Agents) are present and can be updated with no issues.

Field passed:

• Since the BE work is still in flight, check out the following branch locally: ch-dap-enablement-setting-test
• Run GDK on non-SAAS mode: GITLAB_SIMULATE_SAAS=0 gdk start
• Go to the GitLab Duo setting page: /admin/gitlab_duo
• Observe:
  • The DAP enabled setting is visible.
  • If unchecked, other DAP-related (Flows, Foundational Agents) settings are hidden.
  • If checked, other DAP-related settings are visible and can be updated.

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