fix(Portal): throw an error if React.Fragment passed as trigger

[layershifter]

Fixes #3928.

Now we will throw errors in two additional cases:

• when an array of elements is passed, <Popup trigger={[<b />, <b />]} />
• when a React.Fragment is passed <Popup trigger={[<><b /></>} /> as it impossible to use React.cloneElement() with it to assign props

This change is not a breaking as previously these scenarios were impossible, so this PR just adds only meaningful errors.

[codecov-commenter]

Codecov Report

Merging #3998 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #3998   +/-   ##
=======================================
  Coverage   99.84%   99.84%           
=======================================
  Files         183      184    +1     
  Lines        3157     3164    +7     
=======================================
+ Hits         3152     3159    +7     
  Misses          5        5           

Impacted Files	Coverage Δ
src/addons/Portal/Portal.js	100.00% <100.00%> (ø)
src/addons/Portal/utils/validateTrigger.js	100.00% <100.00%> (ø)
src/modules/Popup/Popup.js	98.73% <100.00%> (+0.01%)	⬆️

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