fix(components): [select] iOS keyboard not appear when focus

[MrWeilian]

fix: #11415

问题原因：
iOS系统限制非用户行为的 focus，仅有用户行为直接触发 或者 用户行为后的 回调函数同步触发 .focus() 才能弹起键盘。当前 el-input 组件 readonly 属性当激活下拉框的时候会被改成 false，由于异步更新关系，再触发 el.focus() 就会被系统拦截。

参考链接：

1. input组件，autoFocus自动获取焦点不起作用 ant-design/ant-design-mobile#5256
2. https://stackoverflow.com/questions/6287478/mobile-safari-autofocus-text-field

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[github-actions]

[github-actions]

Hello @MrWeilian, thank you for contributing to element-plus, please see our guideline to see how to make contribution

[github-actions]

🧪 Playground Preview: https://element-plus.run/?pr=11498
Please comment the example via this playground if needed.

[MrWeilian]

playground

[MrWeilian]

参考了设置 multiple 的情况，应该是让用户点了原生 input 先触发键盘弹起，等执行完 readonly 那个计算属性的更新时将焦点 focus 到 el-input 那里面的 input 中。

[chenxch]

键盘是弹出来了👍🏻，但是表现上存在一些问题哦

[MrWeilian]

键盘是弹出来了👍🏻，但是表现上存在一些问题哦

大佬好，什么问题，我跟进下😂

[chenxch]

RPReplay_Final1676125311.MP4

一个是选择后回出现一个下拉框的抖动，类似收齐又展开；然后多选似乎出bug了

[MrWeilian]

RPReplay_Final1676125311.MP4
一个是选择后回出现一个下拉框的抖动，类似收齐又展开；然后多选似乎出bug了

@jw-foss @chenxch hello, I have solved this problem in the new commit. And I added a native input to trigger keyboard instead of to use the multiple native input when device is iOS and el-select is filterable.

[MrWeilian]

RPReplay_Final1676645103.MOV

[jw-foss]

The code LGTM, /cc @chenxch could you help verify this? Thanks 🙇

[MrWeilian]

@chenxch 大佬 cc 👀

[chenxch]

@chenxch 大佬 cc 👀

晚点我看一下哈