Exposed a friend API from the sandbox2 policy builder, which can be friended to components that need it.

PiperOrigin-RevId: 682032921
Change-Id: If8a4cccf907e51aa3deadaba2b254caaf9392c79

Author: Sandboxed API Team

sandboxed_api/sandbox2/policybuilder.h

@@ -782,6 +782,8 @@ class PolicyBuilder final {
   // Returns the current status of the PolicyBuilder.
   absl::Status GetStatus() { return last_status_; }
 
+  const Mounts& mounts() const { return mounts_; }
+
  private:
   friend class PolicyBuilderPeer;  // For testing
   friend class StackTracePeer;