refactor(*): introduce isNumberNaN

window.isNaN(‘lol’); //=> true
Number.isNaN(‘lol’); //=> false

isNaN converts it’s arguments into a Number before checking if it’s NaN.
In various places in the code base, we are checking if a variable is a Number and
NaN (or not), so this can be simplified with this new method (which is not exported on the
global Angular object).

Closes #11242