Allow to set notes title via the API

[milohr]

When using the API to create a new note, according to the documentation, the title field is not available. If I, however, set a value to the title field, it is ignored and instead, it picks the first line fo the content as the title.

It would be better that the endpoint to create the notes would take the title field as a parameter

I'm working on a third-party app to integrate with it, it works on phones with plasma mobile, android and also on desktop.
https://invent.kde.org/kde/buho

[stefan-niedermann]

Dup of #190 and #289 and #55 and #24.

Please see especially last comment in #289

Thank you

[stefan-niedermann]

app looks nice btw :)

[stefan-niedermann]

@korelstar maybe we can mention it in the wiki: https://github.com/nextcloud/notes/wiki