When adding a new form most of the time the spelling variant of the form representation will be the same as the spelling variant of the Lemma. We should pre-fill the spelling variant of a new form's first representation with the spelling variant of the first lemma of the lexeme to make it easier to add a new form and avoid mistakes.
Note: When there is more than one Lemma then we don't pre-fill.
GIVEN I am on a lexeme AND I click "add form" THEN the spelling variant field of the first (auto-added) form representation is pre-filled with the spelling variant of the first lemma of the lexeme it belongs to