fix(mobile): incorrect height of keyboard toolbar in ios (#8653)

### What Changes:
- Fix keyboard height calculation with the `KeyboardToolBarConfig.useScreenHeight = true`. More detials in: https://github.com/toeverything/blocksuite/pull/8645
- Add safe bottom padding for shrinked keyboard toolbar
- Add `VirtualKeyboard` polyfill. Close [AF-1573](https://linear.app/affine-design/issue/AF-1573/virtualkeyboard-polyfill-with-capacitor)
  - Since the `@capacitor/keyboard` dose not implement the `Keyboard.show()` method, this polyfill is not enabled now.

packages/frontend/apps/ios/src/setup.ts

@@ -1,3 +1,6 @@
 import '@affine/core/bootstrap/browser';
 import '@affine/component/theme';
 import '@affine/core/mobile/styles/mobile.css';
+
+// TODO(@L-Sun) Uncomment this when the `show` method implement by `@capacitor/keyboard` in ios
+// import './virtual-keyboard';