Remove setTimeout from useKWindowDimensions and useKResponsiveWindow test files

[MisRob]

• Remove setTimeout from useKWindowDimensions and useKResponsiveWindow test files (introduced here and here)
• Keep the tests but use a more reliable timing technique instead of using setTimeout which may cause the following problems:

  flagging that using setTimeout in these tests like this could make them flaky - there's no guarantee that the content of the setTimeout will execute before the test itself is torn down, or that failures will even be registered (by @rtibbles)

[MisRob]

@rtibbles suggests using $nextTick

[Soren568]

Hi, I would like to work on this. Could you assign it to me?

[MisRob]

Hi @Soren568, yes, thank you!

[Soren568]

@MisRob I initiated the PR above, this is my first PR for kolibri so please let me know if there is anything I missed.

[MisRob]

Thank you, @Soren568

[MisRob]

Closed by #491