Add test-case to see when components are unmounted

Does currently work correctly, more info is needed in the ticket

re #18

examples/src/components/core/lifecycle/OnUnmounted.stories.ts

@@ -0,0 +1,55 @@
+import { html } from '@muban/template';
+import type { Story } from '@muban/storybook/dist/client/preview/types-6-0';
+import { ref } from '@vue/reactivity';
+import { computed } from '@vue/runtime-core';
+import { bind, defineComponent, onMounted, onUnmounted } from '../../../../../src';
+
+export default {
+  title: 'core/lifecycle/onUnmounted',
+};
+
+const Child = defineComponent({
+  name: 'child',
+  setup() {
+    console.log('setup');
+    onMounted(() => {
+      console.log('+ child mounted');
+    });
+    onUnmounted(() => {
+      console.log('- child unmounted');
+    });
+    return [];
+  },
+});
+
+/**
+ * Tries to test if a child component stays mounted when parent is set to display:none
+ */
+export const Default: Story = () => ({
+  component: defineComponent({
+    name: 'onUnmounted',
+    components: [Child],
+    refs: {
+      content: 'content',
+      toggle: 'toggle',
+    },
+    setup({ refs }) {
+      const isVisible = ref<boolean>(true);
+
+      return [
+        bind(refs.toggle, {
+          checked: isVisible,
+        }),
+        bind(refs.content, {
+          style: { display: computed(() => (isVisible.value ? 'block' : 'none')) },
+        }),
+      ];
+    },
+  }),
+  template: () => html` <div data-component="onUnmounted">
+    <div><input data-ref="toggle" type="checkbox" />toggle</div>
+    <div data-ref="content">
+      <div data-component="child">Child content</div>
+    </div>
+  </div>`,
+});