fix(dropdown): fix incorrect behavior of nested dropdown (#4739)

[MilaLysenko]

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Closes: #4739

[codecov]

Codecov Report

Merging #4950 into development will decrease coverage by 0.04%.
The diff coverage is 47.05%.

@@               Coverage Diff               @@
##           development    #4950      +/-   ##
===============================================
- Coverage        74.79%   74.74%   -0.05%     
===============================================
  Files              277      278       +1     
  Lines             8434     8449      +15     
  Branches          1602     1602              
===============================================
+ Hits              6308     6315       +7     
- Misses            1678     1687       +9     
+ Partials           448      447       -1

Impacted Files	Coverage Δ
src/dropdown/public_api.ts	100% <100%> (ø)	⬆️
src/dropdown/bs-dropdown.module.ts	93.33% <100%> (+0.47%)	⬆️
src/dropdown/bs-dropdown-nested.directive.ts	35.71% <35.71%> (ø)
src/chronos/i18n/pl.ts	71.79% <0%> (-2.57%)	⬇️
src/chronos/i18n/cs.ts	86.44% <0%> (ø)	⬆️
src/chronos/i18n/sk.ts	82.97% <0%> (ø)	⬆️
src/chronos/i18n/it.ts	100% <0%> (+28.57%)	⬆️

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[codecov]

Codecov Report

Merging #4950 into development will increase coverage by 0.02%.
The diff coverage is 47.05%.

@@               Coverage Diff               @@
##           development    #4950      +/-   ##
===============================================
+ Coverage        74.71%   74.74%   +0.02%     
===============================================
  Files              276      278       +2     
  Lines             8385     8449      +64     
  Branches          1594     1602       +8     
===============================================
+ Hits              6265     6315      +50     
- Misses            1677     1687      +10     
- Partials           443      447       +4     

Impacted Files	Coverage Δ
src/dropdown/bs-dropdown-nested.directive.ts	35.71% <35.71%> (ø)
src/dropdown/bs-dropdown.module.ts	93.33% <100.00%> (+0.47%)	⬆️
src/dropdown/public_api.ts	100.00% <100.00%> (ø)
src/utils/warn-once.ts	50.00% <0.00%> (-50.00%)	⬇️
...themes/bs/bs-datepicker-day-decorator.directive.ts	81.81% <0.00%> (-18.19%)	⬇️
src/utils/triggers.ts	66.19% <0.00%> (-3.81%)	⬇️
src/chronos/i18n/pl.ts	71.79% <0.00%> (-2.57%)	⬇️
...c/datepicker/bs-daterangepicker-input.directive.ts	24.41% <0.00%> (-1.20%)	⬇️
src/datepicker/bs-datepicker-input.directive.ts	45.20% <0.00%> (-0.63%)	⬇️
src/chronos/i18n/cs.ts	86.44% <0.00%> (ø)
... and 19 more

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[valorkin]

We should pair review this one

[higurush]

This one works quite well. However, a little suggestion though, is to implement some kind of a timer, since with a long, page sized menu, the submenu instantly disappears.
And if you implement the timer itself, you can see that the menus are still overlapping each other.

Another improvement could be to place the submenus where the parent option is, instead of just top:0

this.renderer.setStyle(nestedMenu , 'top', this.elem.nativeElement.offsetTop + 'px');

[deltaGPhys]

Is anoybody monitoring this PR? This bug makes the library useless for many.