Nested tables don't work with fixed columns

[menosprezzi]

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

Reproduction link

https://codepen.io/menosprezzi/pen/GRNybBX

Steps to reproduce

1. Open a new codepen of https://ant.design/components/table/#components-table-demo-nested-table
2. Set Date column as fixed in the NestedTable component
3. Resize the space available in the screen

What is expected?

Render fixed columns in the nested table.

What is actually happening?

It renders the nested table without the fixed effect applied to the desired column which breaks the responsivity

Environment	Info
antd	4.12.3
React	16.14.0
System	MacOS Big Sur; Windows 10
Browser	Chrome 88; New Edge

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Check the CSS code to preview the hack that I made to accomplish the correct experience.

[zombieJ]

https://codesandbox.io/s/nested-tables-antd4130-forked-tomgk?file=/index.js

Is this missing scroll x?

[menosprezzi]

@zombieJ Hello there!
Wow! I didn't realize that this prop will fix that behaviour. Great!
I think that will be the right thing to do if we put this prop in the nested table example on the Docs, so other sloppy devs (like I was 😛 ) can go with it and don't break their heads hehe

Should I go with a PR?

Thanks!