chore: refactor read scheme to openapi from kubernetes api definition

Previously, only a single embedded Kubernetes API version could be specified, resulting in a lack of support for certain GVKs.
To address this, the goal is to create and utilize a unified scheme that consolidates Kubernetes API definitions.
As a preliminary step, the current method of loading API definitions will be improved.

kyaml/openapi/kubernetesapi/v1_21_2/swagger_test.go

@@ -0,0 +1,43 @@
+// Copyright 2026 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package v1_21_2 //nolint:revive // The package name is part of the public API.
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAssetCompatibility(t *testing.T) {
+	b, err := Asset(assetName)
+	require.NoError(t, err)
+	digest := sha256.Sum256(b)
+	require.Equal(t, "5d171b55e9601912807a870d73ffe70bb306f5889a00e76986042a0f2d7b6bc2",
+		hex.EncodeToString(digest[:]))
+	info, err := AssetInfo(assetName)
+	require.NoError(t, err)
+	require.Equal(t, int64(3469475), info.Size())
+	require.Equal(t, "swagger.pb", info.Name())
+
+	backslashName := "kubernetesapi\\v1_21_2\\swagger.pb"
+	_, err = Asset(backslashName)
+	require.NoError(t, err)
+	children, err := AssetDir("kubernetesapi/v1_21_2")
+	require.NoError(t, err)
+	require.Equal(t, []string{"swagger.pb"}, children)
+	_, err = AssetDir(assetName)
+	require.Error(t, err)
+
+	b[0] ^= 0xff
+	again := MustAsset(assetName)
+	require.NotEqual(t, b[0], again[0], "Asset must return a fresh byte slice")
+	_, err = Asset("missing")
+	require.Error(t, err)
+}
+
+func TestAssetNames(t *testing.T) {
+	require.Equal(t, []string{assetName}, AssetNames())
+}