Add the ability to hide a Form Item

• I have searched the issues of this repository and believe that this is not a duplicate.

What problem does this feature solve?

It would be nice to be able to toggle the visibility of a form item by toggling a boolean flag, such as hidden. By default the value would be false, meaning that is is not hidden.

This would prevent having to wrap the component within an if statement to deduce whether or not the component is visible.

What does the proposed API look like?

By default, all form items should be visible, e.g:

<Form.Item label="Username">
    <Input type="text" />
</Form.Item>

Setting the hidden prop to true, would hide the form item, e.g:

<Form.Item label="Username" hidden={true}>
    <Input type="text" />
</Form.Item>

[yoyo837]

掩耳盗铃，隐藏和没有是两回事

[henryzp]

@yoyo837

<Form.Item label="Username" noStyle>
    <Input type="text" type="hidden" />
</Form.Item>