This rev. changes the layout of *editable* list views to a fixed
layout. This means that we are now responsible of the width of
each column. To do that, we associate with each field type a
factor, and the higher the factor is, the larger the column will
be (w.r.t. the others). This default value can be overriden in the
arch.
The fixed layout allows to remove the absolute positionning of
widgets inside editable lists (done in the next commit).
Part of task 1915702
Co-authored-by: Martin Geubelle <mge@odoo.com>
