elevate: add ParsePolicy helper

pkg/elevate/policy.go

@@ -65,6 +65,11 @@ func (p *Policy) Marshal() ([]byte, error) {
 	return yaml.Marshal(p)
 }
 
+// ParsePolicy parses YAML data into a Policy.
+func ParsePolicy(data []byte, p *Policy) error {
+	return yaml.Unmarshal(data, p)
+}
+
 // PolicyStore manages a disk-backed global policy and in-memory session policies.
 type PolicyStore struct {
 	mu     sync.RWMutex