Top count displays how many resolved discussions

Added a white background to the edit form on highlighted notes

Closes #18101

Fixes note's action bar background color when note is highlighted

Also changed to allow the CSS to decide what should be hidden when editting

Use lowercase letters and shorthand values for HEX colors where
possible.

Discussed in #14299.

First, the autosize library was being too controlling and removed the
`resize` property from any elements to which it was attached, removing
the drag handle.

Second, we detect when the user manually resizes an autosize textarea,
and then remove the autosize behavior from it and increase its
max-height.

This should allow for the best of both worlds.

Closes #12832