fix(ngAria): ensure boolean values for aria-hidden and aria-disabled
fix(ngAria): ensure boolean values for aria-hidden and aria-disabled

aria-hidden should mirror the boolean representation of their ng-*
counterpart (ng-show, ng-hide) instead of their actual value. Same
applies to aria-disabled and ng-disabled

Closes #11365

ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js