Switch to stretchr/testify / mockery for mocks

testify is used throughout the codebase; this switches mocks from
gomock to testify with the help of mockery for code generation.

Handlers and mocks in test/utils/oidc are moved to a new package:
mockery operates package by package, and requires packages to build
correctly; test/utils/oidc/testserver.go relies on the mocks and fails
to build when they are removed. Moving the interface and mocks to a
different package allows mockery to process that package without
having to build testserver.go.

Signed-off-by: Stephen Kitt <skitt@redhat.com>

test/utils/oidc/handlers/mock_token_handler.go

@@ -0,0 +1,119 @@
+/*
+Copyright The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+/*
+Copyright The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Code generated by mockery v2.40.3. DO NOT EDIT.
+
+package handlers
+
+import mock "github.com/stretchr/testify/mock"
+
+// MockTokenHandler is an autogenerated mock type for the TokenHandler type
+type MockTokenHandler struct {
+	mock.Mock
+}
+
+type MockTokenHandler_Expecter struct {
+	mock *mock.Mock
+}
+
+func (_m *MockTokenHandler) EXPECT() *MockTokenHandler_Expecter {
+	return &MockTokenHandler_Expecter{mock: &_m.Mock}
+}
+
+// Token provides a mock function with given fields:
+func (_m *MockTokenHandler) Token() (Token, error) {
+	ret := _m.Called()
+
+	if len(ret) == 0 {
+		panic("no return value specified for Token")
+	}
+
+	var r0 Token
+	var r1 error
+	if rf, ok := ret.Get(0).(func() (Token, error)); ok {
+		return rf()
+	}
+	if rf, ok := ret.Get(0).(func() Token); ok {
+		r0 = rf()
+	} else {
+		r0 = ret.Get(0).(Token)
+	}
+
+	if rf, ok := ret.Get(1).(func() error); ok {
+		r1 = rf()
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}
+
+// MockTokenHandler_Token_Call is a *mock.Call that shadows Run/Return methods with type explicit version for method 'Token'
+type MockTokenHandler_Token_Call struct {
+	*mock.Call
+}
+
+// Token is a helper method to define mock.On call
+func (_e *MockTokenHandler_Expecter) Token() *MockTokenHandler_Token_Call {
+	return &MockTokenHandler_Token_Call{Call: _e.mock.On("Token")}
+}
+
+func (_c *MockTokenHandler_Token_Call) Run(run func()) *MockTokenHandler_Token_Call {
+	_c.Call.Run(func(args mock.Arguments) {
+		run()
+	})
+	return _c
+}
+
+func (_c *MockTokenHandler_Token_Call) Return(_a0 Token, _a1 error) *MockTokenHandler_Token_Call {
+	_c.Call.Return(_a0, _a1)
+	return _c
+}
+
+func (_c *MockTokenHandler_Token_Call) RunAndReturn(run func() (Token, error)) *MockTokenHandler_Token_Call {
+	_c.Call.Return(run)
+	return _c
+}
+
+// NewMockTokenHandler creates a new instance of MockTokenHandler. It also registers a testing interface on the mock and a cleanup function to assert the mocks expectations.
+// The first argument is typically a *testing.T value.
+func NewMockTokenHandler(t interface {
+	mock.TestingT
+	Cleanup(func())
+}) *MockTokenHandler {
+	mock := &MockTokenHandler{}
+	mock.Mock.Test(t)
+
+	t.Cleanup(func() { mock.AssertExpectations(t) })
+
+	return mock
+}