[FIX] web: sort and onchange in tabbed editable x2m

Two attempts of dealing with sorting (and resequencing) in tabbed (multi-pages)
x2many editable lists (see odoo/odoo@c2563db and odoo/odoo@983c7ae) have been
previously done, using a static attribute (`keepChangesUnsorted`) on the
datapoint.

This solution sadly only covers both cases separately, not if they are combined.
Morever, onchanges were not correctly managed in neither of these two cases.

A new approach is used here, by "freezing" and "unfreezing" the datapoint when
needed, which is more flexible.

Some modifications have been introduced:
 - when ordering a x2many, all records are now considered (and not only the
   records on the current page) ; an additional read is thus done on the sorted
   field for all records in the x2many relation
 - `setSort` is now asynchronous as a `read` might be needed

0 files changed, 0 insertions, 0 deletions