feat(Popup): add mountNode and mountDocument

[layershifter]

BREAKING CHANGES

context was renamed to mountNode in PortalInner to be consistent. It matches SUIR naming.

Before

<PortalInner context={document.body} />

After

<PortalInner mountNode={document.body} />

Two props added to Popup component

1. mountNode to define an element where popup should be bound to:

<Popup mountNode={document.body} />
<Popup mountNode={document.getElementById('popup-areas')} />

2. mountDocument to define a target for listeners:

<Popup mountDocument={innerDocument} />

[codecov]

Codecov Report

Merging #1288 into master will increase coverage by 0.01%.
The diff coverage is 94.73%.

@@            Coverage Diff             @@
##           master    #1288      +/-   ##
==========================================
+ Coverage   72.83%   72.85%   +0.01%     
==========================================
  Files         747      747              
  Lines        5654     5658       +4     
  Branches     1632     1633       +1     
==========================================
+ Hits         4118     4122       +4     
  Misses       1529     1529              
  Partials        7        7

Impacted Files	Coverage Δ
...ckages/react/src/components/Portal/PortalInner.tsx	100% <100%> (ø)	⬆️
packages/react/src/components/Popup/Popup.tsx	69.04% <92.3%> (+0.75%)	⬆️

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