Fix/blockquote commands #5746

…n the cursor is in a `listItem`, setting or unsetting `blockquote` is allowed.

…is on the first paragraph of a `listItem`, setting `blockquote` should be allowed, and the `blockquote` will wrap the entire list.

…en the cursor is on the first element of a list item, setting `blockquote` will wrap the entire list; and when the cursor is on the second element of a list item, setting `blockquote` will only wrap the second element.