Updated property 'isOpen' in popover.directive.ts

[npacucci]

Updated property 'isOpen' into 'show' and 'hide' methods. Through this is possible to use 'toggle' method together with 'show' and 'hide' methods.
Example: if you want to toggle popover by using a button and close it also by click another button inside the popover.

[codecov-io]

Codecov Report

Merging #1765 into development will increase coverage by 0.05%.
The diff coverage is 100%.

@@               Coverage Diff               @@
##           development    #1765      +/-   ##
===============================================
+ Coverage        85.41%   85.47%   +0.05%     
===============================================
  Files               85       85              
  Lines             2290     2292       +2     
  Branches           300      300              
===============================================
+ Hits              1956     1959       +3     
+ Misses             235      234       -1     
  Partials            99       99

Impacted Files	Coverage Δ
src/popover/popover.directive.ts	100% <100%> (+2.7%)	✅

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[npacucci]

@valorkin it's possible to merge this? Thanks! 😄

[valorkin]

thanks for help! ;)