refactor: use struct types for claim related types (#283)

* oidc: add regression tests for token claim json

this helps to verify that the same JSON is produced,
after these types are refactored.

* refactor: use struct types for claim related types

BREAKING CHANGE:
The following types are changed from interface to struct type:

- AccessTokenClaims
- IDTokenClaims
- IntrospectionResponse
- UserInfo and related types.

The following methods of OPStorage now take a pointer to a struct type,
instead of an interface:

- SetUserinfoFromScopes
- SetUserinfoFromToken
- SetIntrospectionFromToken

The following functions are now generic, so that type-safe extension
of Claims is now possible:

- op.VerifyIDTokenHint
- op.VerifyAccessToken
- rp.VerifyTokens
- rp.VerifyIDToken

- Changed UserInfoAddress to pointer in UserInfo and
IntrospectionResponse.
This was needed to make omitempty work correctly.
- Copy or merge maps in IntrospectionResponse and SetUserInfo

* op: add example for VerifyAccessToken

* fix: rp: wrong assignment in WithIssuedAtMaxAge

WithIssuedAtMaxAge assigned its value to v.maxAge, which was wrong.
This change fixes that by assiging the duration to v.maxAgeIAT.

* rp: add VerifyTokens example

* oidc: add standard references to:

- IDTokenClaims
- IntrospectionResponse
- UserInfo

* only count coverage for `./pkg/...`

pkg/oidc/introspection_test.go

@@ -0,0 +1,78 @@
+package oidc
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestIntrospectionResponse_SetUserInfo(t *testing.T) {
+	tests := []struct {
+		name  string
+		start *IntrospectionResponse
+		want  *IntrospectionResponse
+	}{
+		{
+
+			name:  "nil claims",
+			start: &IntrospectionResponse{},
+			want: &IntrospectionResponse{
+				Subject:         userInfoData.Subject,
+				Username:        userInfoData.PreferredUsername,
+				Address:         userInfoData.Address,
+				UserInfoProfile: userInfoData.UserInfoProfile,
+				UserInfoEmail:   userInfoData.UserInfoEmail,
+				UserInfoPhone:   userInfoData.UserInfoPhone,
+				Claims:          userInfoData.Claims,
+			},
+		},
+		{
+
+			name: "merge claims",
+			start: &IntrospectionResponse{
+				Claims: map[string]any{
+					"hello": "world",
+				},
+			},
+			want: &IntrospectionResponse{
+				Subject:         userInfoData.Subject,
+				Username:        userInfoData.PreferredUsername,
+				Address:         userInfoData.Address,
+				UserInfoProfile: userInfoData.UserInfoProfile,
+				UserInfoEmail:   userInfoData.UserInfoEmail,
+				UserInfoPhone:   userInfoData.UserInfoPhone,
+				Claims: map[string]any{
+					"foo":   "bar",
+					"hello": "world",
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tt.start.SetUserInfo(userInfoData)
+			assert.Equal(t, tt.want, tt.start)
+		})
+	}
+}
+
+func TestIntrospectionResponse_GetAddress(t *testing.T) {
+	// nil address
+	i := new(IntrospectionResponse)
+	assert.Equal(t, &UserInfoAddress{}, i.GetAddress())
+
+	i.Address = &UserInfoAddress{PostalCode: "1234"}
+	assert.Equal(t, i.Address, i.GetAddress())
+}
+
+func TestIntrospectionResponse_MarshalJSON(t *testing.T) {
+	got, err := json.Marshal(&IntrospectionResponse{
+		UserInfoProfile: UserInfoProfile{
+			PreferredUsername: "muhlemmer",
+		},
+	})
+	require.NoError(t, err)
+	assert.Equal(t, string(got), `{"active":false,"username":"muhlemmer","preferred_username":"muhlemmer"}`)
+}