Content update: presentation of nêpit

[fbanados]

nêpit currently breaks the relabelling:

Also for nêpiyit:

[fbanados]

There's two things going on:

• For the None" The text in a Lexical Entry is Optional[str]. At serializing time, we should replace the None with a "" empty string.
• The arrow messaging for an Initial Change is directly coded in CreeDictionary/API/search/presentation.py, following this comment. It's ok if that is the text that should be presented, but it may benefit from some heading at least, and we should discuss whether this should be placed somewhere else instead of directly encoded in python as to make the dictionary more language agnostic.