Android: Enhancement to add drop down for groups when creating a new note

[Fmstrat]

I should be able to select a group I already created when making a new note, I'm thinking a dropddown list on the New Note dialog.

@qkzoo reference: https://github.com/Fmstrat/ownnote/issues/137

[Abyss777]

Please add drop down list not only in new note, but in editing note too. Now it is impossible to edit group of existing note.