dome: optimize FloatBotton demo style (#42980)

* docs: FloatBotton open 属性说明

* test: update snapshots

* demo: add controlled demo

* demo: update demo

* feat: add warning

* feat: update warning

* demo: update controlled demo

* demo: prettify demo style

* demo: update snapshots

---------

Co-authored-by: 二货机器人 <smith3816@gmail.com>

components/float-button/__tests__/__snapshots__/demo-extend.test.ts.snap

@@ -855,6 +855,7 @@ Array [
     aria-checked="true"
     class="ant-switch ant-switch-checked"
     role="switch"
+    style="margin: 16px;"
     type="button"
   >
     <div

components/float-button/__tests__/__snapshots__/demo.test.ts.snap

@@ -645,6 +645,7 @@ Array [
     aria-checked="true"
     class="ant-switch ant-switch-checked"
     role="switch"
+    style="margin:16px"
     type="button"
   >
     <div

components/float-button/demo/controlled.tsx

@@ -20,7 +20,7 @@ const App: React.FC = () => {
         <FloatButton />
         <FloatButton icon={<CommentOutlined />} />
       </FloatButton.Group>
-      <Switch onChange={onChange} checked={open} />
+      <Switch onChange={onChange} checked={open} style={{ margin: 16 }} />
     </>
   );
 };