fix(Popup): fix broken background with pointing and FocusTrap

[layershifter]

Fixes #1679.

Problem

In master we have already resolved this issue by #1565, however we need to provide a fix without breaking changes for now.

Before

After

Test snippet

import * as React from 'react'
import { Button, Flex, Popup, popupFocusTrapBehavior } from '@stardust-ui/react'

const plainContentStyle = {
  zIndex: 1000,
  padding: 5,
}

const PopupExample = () => (
  <Flex vAlign='center' space='between' styles={{ padding: '50px', height: '500px', backgroundColor: 'orange' }}>
    <Popup content="Hello from popup!" pointing open accessibility={popupFocusTrapBehavior}>
      <Button icon="expand"/>
    </Popup>

    <Popup open content={<p style={plainContentStyle}>Plain popup content rendered 'as is'.</p>}>
      <Button icon="expand" content="Popup with plain content"/>
    </Popup>
    <Popup open accessibility={popupFocusTrapBehavior}
           content={<p style={plainContentStyle}>Plain popup content rendered 'as is'.</p>}>
      <Button icon="expand" content="Popup with plain content"/>
    </Popup>

    <Popup
      open
      content={{ content: <p style={plainContentStyle}>Popup content rendered in wrapper.</p> }}
    >
      <Button icon="expand" content="Popup with wrapped content"/>
    </Popup>
  </Flex>
)

export default PopupExample

[DustyTheBot]

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[codecov]

Codecov Report

Merging #1689 into chore/0.34.2 will decrease coverage by 0.01%.
The diff coverage is 0%.

@@               Coverage Diff                @@
##           chore/0.34.2    #1689      +/-   ##
================================================
- Coverage         71.43%   71.42%   -0.02%     
================================================
  Files               848      848              
  Lines              6942     6943       +1     
  Branches           2007     1988      -19     
================================================
  Hits               4959     4959              
- Misses             1977     1978       +1     
  Partials              6        6

Impacted Files	Coverage Δ
...t/src/themes/teams/components/Popup/popupStyles.ts	25% <0%> (-8.34%)	⬇️

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[kuzhelov]

actually, this should also apply in case if render function is provided as an argument :( as in that case slot component will be also replaced. So, I think that we may just check that this is not an object or primitive

[layershifter]

Adjusted to handle render() callback cases:

    <Popup open trigger={<Button icon="expand"/>} content={render => render(
      {},
      (ComponentType, props) => (
        <p style={{ zIndex: 1000, padding: 5 }}>Plain popup content rendered 'as is'.</p>
      ),
    )}/>
    <Popup open trigger={<Button icon="expand"/>} pointing content={render => render(
      {},
      (ComponentType, props) => (
        <div {...props} style={{ zIndex: 1000, padding: 5}}>
          Plain popup content rendered 'as is'.
        </div>
      ),
    )}/>