test: add full OIDC fake IDP (#9317)

* test: implement fake OIDC provider with full functionality
* Refactor existing tests

coderd/util/syncmap/map.go

@@ -0,0 +1,77 @@
+package syncmap
+
+import "sync"
+
+// Map is a type safe sync.Map
+type Map[K, V any] struct {
+	m sync.Map
+}
+
+func New[K, V any]() *Map[K, V] {
+	return &Map[K, V]{
+		m: sync.Map{},
+	}
+}
+
+func (m *Map[K, V]) Store(k K, v V) {
+	m.m.Store(k, v)
+}
+
+//nolint:forcetypeassert
+func (m *Map[K, V]) Load(key K) (value V, ok bool) {
+	v, ok := m.m.Load(key)
+	if !ok {
+		var empty V
+		return empty, false
+	}
+	return v.(V), ok
+}
+
+func (m *Map[K, V]) Delete(key K) {
+	m.m.Delete(key)
+}
+
+//nolint:forcetypeassert
+func (m *Map[K, V]) LoadAndDelete(key K) (actual V, loaded bool) {
+	act, loaded := m.m.LoadAndDelete(key)
+	if !loaded {
+		var empty V
+		return empty, loaded
+	}
+	return act.(V), loaded
+}
+
+//nolint:forcetypeassert
+func (m *Map[K, V]) LoadOrStore(key K, value V) (actual V, loaded bool) {
+	act, loaded := m.m.LoadOrStore(key, value)
+	if !loaded {
+		var empty V
+		return empty, loaded
+	}
+	return act.(V), loaded
+}
+
+func (m *Map[K, V]) CompareAndSwap(key K, old V, new V) bool {
+	return m.m.CompareAndSwap(key, old, new)
+}
+
+func (m *Map[K, V]) CompareAndDelete(key K, old V) (deleted bool) {
+	return m.m.CompareAndDelete(key, old)
+}
+
+//nolint:forcetypeassert
+func (m *Map[K, V]) Swap(key K, value V) (previous any, loaded bool) {
+	previous, loaded = m.m.Swap(key, value)
+	if !loaded {
+		var empty V
+		return empty, loaded
+	}
+	return previous.(V), loaded
+}
+
+//nolint:forcetypeassert
+func (m *Map[K, V]) Range(f func(key K, value V) bool) {
+	m.m.Range(func(key, value interface{}) bool {
+		return f(key.(K), value.(V))
+	})
+}