Fix it so that upvoting or downvoting a revealed thresholded comment
doesn't hide it again.
The fix is to explicitly store a `data-show-thresholded` flag on the
comment, instead of manually hiding elements with jQuery, and to morph
the comment HTML instead of replacing it so that the state isn't lost
after voting. Alpine.js is used for this, which isn't strictly necessary,
but is useful to test the library before adopting it on a wider scale.
https://alpinejs.dev/start-here
Move Javascript files from app/components/**/*.js back to app/javascript/src/javascripts/*.js.
This way Javascript files are in one place, which simplifies import paths and makes it
easier to see all Javascript at once.
