Imports of package cache

PathSynopsis
container/listPackage list implements a doubly linked list.
github.com/open-policy-agent/opa/astDeprecated: This package is intended for older projects transitioning from OPA v0.x and will remain for the lifetime of OPA v1.x, but its use is not recommended.
github.com/open-policy-agent/opa/utilPackage util provides generic utilities used throughout the policy engine.
syncPackage sync provides basic synchronization primitives such as mutual exclusion locks.