Support tabbing and changing focus to a select component

[ztplz]

Fix ant-design/ant-design#14503

[ant-design-bot]

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[ztplz]

@afc163 @zombieJ tslint 那个private public顺序改一下

[zombieJ]

ant-design/ant-design#14503 里的 Select，其实是可以通过 focus 后按 下/Enter 键打开后输入的。修的话应该是 focus 后按任意键都打开 dropdown 并且在 input 里输入刚才键入的字符。

[ztplz]

是可以通过enter建输入 我也不知道算不算bug 但是我看他意思是tab到select后 focus并可以输入

[zombieJ]

这不算是 BUG，应该算是需要优化的点。否则不够直观。

[bryanberger]

any movement on this? also tabFoucs should be spelled as tabFocus

[JonathanLee-LX]

这个地方还是建议能优化一下，因为经常会有一些通过全局快捷键打开搜索框的需求，现在在使用focus方法聚焦之后，要进行搜索还需要按一下enter键。 @zombieJ

[zombieJ]

@JonathanLee-LX antd@4.0 / rc-select@10.0 中会配合无障碍对此进行优化。

[fgiarritiello]

Can this be merged please?

[zombieJ]

@fgiarritiello, already support in new rc-select.