feat(browser): 添加全屏功能- 在 WebViewActivity 中实现全屏切换功能 (#4404)

- 在菜单中添加全屏选项
- 更新多语言字符串文件，添加全屏相关翻译

Co-authored-by: SunQAQ <sunqi87c6@gmail.com>

app/src/main/res/values/strings.xml

@@ -915,6 +915,7 @@
     <string name="double_page_horizontal">Tablet/Landscape Dual Page</string>
     <string name="open_in_browser">open in browser</string>
     <string name="copy_url">copy url</string>
+    <string name="full_screen">full screen</string>
     <string name="open_fun">open function</string>
     <string name="use_browser_open">Is it opened in an external browser?</string>
     <string name="see">see</string>
@@ -1174,4 +1175,5 @@
     <string name="read_aloud_read_phone_state_permission_rationale">阅读需要读取手机状态实现来电期间暂停朗读功能</string>
     <string name="read_aloud_by_media_button_title">耳机按键启动朗读</string>
     <string name="read_aloud_by_media_button_summary">通过耳机按键来启动朗读</string>
+    <string name="fullscreen" translatable="false">全屏</string>
 </resources>