Add ability to increase the font size for lists

[karmatosed]

As I mentioned in #5775, for lists having the font size option would be good also. This came up in recent testing, there is a strong argument that for any text we should allow that option.

With a paragraph we finally see how to change the font size, this is missing for the quote block. The same change for the font size is missing for the list block.

[karmatosed]

I am closing as this on every block would be part of phase 2 if at all.

[aleciabeck]

We definitely need to be able to change the font size of lists and of single characters inside a block without changing the size of the rest of the text in a block