Initial QSfera import

Server/vendor/github.com/open-policy-agent/opa/v1/ast/slices.go

@@ -0,0 +1,15 @@
+// Copyright 2026 The OPA Authors.  All rights reserved.
+// Use of this source code is governed by an Apache2
+// license that can be found in the LICENSE file.
+
+package ast
+
+// CountFunc counts the number of items in a slice S that satisfy predicate function f.
+func CountFunc[T any, S ~[]T](items S, f func(T) bool) (n int) {
+	for i := range items {
+		if f(items[i]) {
+			n++
+		}
+	}
+	return n
+}