Implement group-based access for Organization Secrets

[evgeniy-scherbina]

Implement group-based access for Organization Secrets based on how it's done for Template Access.

Sub-issues:

• Extend org_secrets table with a GroupACL map, similar to how it's done for templates table.
• Provide API to modify this GroupACL map.
• Update DBAuthz wrappers to take into account group-based access.