Checkbox lists are not indented

[stefan-niedermann]

In the Single Note Widget, nested checkbox lists are not intendet.

This is caused by calling replaceCheckboxesWithEmoji(), which also removes the leading dashes (-). The parser then is not able to recognize a nested list anymore.

A fix is already work in progress.

(Original issue reported by @fl0rianB : https://github.com/nextcloud/notes/issues/737)