fix: add ariaHidden to br hack nodes

[nperez0111]

In the same spirit as #118 this makes the BR hack node be hidden to screen readers

[marijnh]

These nodes are present in most web-based editors, and screen readers seem to be able to handle them gracefully in my experience. What kind of issues are you running into, when using a screen reader, that would require this attribute?

[miguelcaro]

@marijnh one of our clients report that the
it is been announced by the screen reader.
please take a look on the following image

c.c. @nperez0111

[marijnh]

How does the reader announce these? What do they sound like?

[miguelcaro]

How does the reader announce these? What do they sound like?

Don't know to be honest they just sent us this image with
been announced by the NVDA speech viewer, like you can see in the image above

[marijnh]

What I'm seeing with NVDA is that it says 'blank' on blank lines, whether they have the <br> or not, and nothing more. Until I actually understand the problem, I'm afraid I'm not going to merge this patch.