When user doesn't use automatically generated move lines, he/she can
copy a list on Serial Number in the `lot_name` field, it will create a
new move line for each value with the corresponding `lot_name`.
Also, as we need a line break char to split the field value, we need the
field is a testarea as a simple input can't have value with breaklines.
So, the `lot_name` need to be a field text instead of char.
Task #2028780closesodoo/odoo#35532
Signed-off-by: Simon Lejeune (sle) <sle@openerp.com>