Runtime should limit privileges

[xibz]

• runtime should support that ReadOnlyRootfs is false
• runtime should support Privileged is true
• runtime should support RunAsUser
• should return error if RunAsGroup is set without RunAsUser
• runtime should support RunAsUserName
• runtime should support SupplementalGroups
• runtime should support setting Capability
• runtime should support Privileged is false
• runtime should support RunAsGroup
• runtime should support that ReadOnlyRootfs is true