Fix antd palette preview cosmetic issues

[lovtsovaik]

palette-antd 4.2.0-dev.2

1. Suggest to add previewLayout={"stretch"} into Variant for the next components:

   • Carousel,
   • Grid,
   • Slider,
   • Timeline with modes

2. Menu(horizontal). It seems we need to remove defaultOpenKeys because opened popup overlaps the menu itself:

3. Switchers in Carousel are white and are vor visible. They can be visible only not-white background Suggest to make the switchers black, as a text.

[lovtsovaik]

Grid, slider, menu - ok

1. Timeline now contains extra Menu component:

2. Carousel has a blue background instead of black switchers

New problems after formatting (https://github.com/react-buddy/demo-antd-v4/commit/b85aca31975c13ed302d3760c2a8942924f11e4b):

• Button: some components one-line, some multiline (it was fixed after my first testing and now broken again...)
• extra spaces, comas were added. It doesn't break the behavior but looks useless.

[HegelPro]

@lovtsovaik

2. The blue color has been taking from antd doc

About adding formatting, we need to discuss whether to add or not