Add support for YouTube Shorts blocking on mobile home page

[outsparkled]

The code responsible for blocking shorts on the home page currently uses the is-shorts attribute on the ytd-rich-shelf-renderer element to detect the Shorts section. This however only works on desktop, since YouTube on mobile (m.youtube.com) does not use this attribute.

I did some poking around on the mobile home page and found that the grid-shelf-view-model on the mobile website seems to be used exclusively for the Shorts section. This could be used to block shorts on mobile as well by removing all grid-shelf-view-model elements.

If you are interested, I would be happy to make a pull request with such a change.