[FIX] point_of_sale: ui stuck when product has grouped tax

To reproduce:

1. Create a grouped tax with multiple taxes. Reorder the tax
   items. (Important step.)
2. Assign tax to the product.
3. Open pos loading the product.
4. a. [BUG] If pos config is tax-included -> non-responsive ui.
4. b. [BUG] If pos config is tax-excluded:
          Add the product. -> non-responsive ui.

Fix:

With the new reactivity in owl, mutating reactive objects will
trigger rerender. However, computing tax amount of orderline
or product with grouped taxes result to mutation of a reactive
object, triggering an infinite render (render -> compute with
mutation -> will trigger another render -> ...).

The call to sort is mutating the reactive array referred by
`children_tax_ids`. To prevent this infinite render, the solution
is to use a copy of the array when sorting the taxes.

OPW-2816546

closes odoo/odoo#88245

X-original-commit: b273056a12a34fec75d980e8a4a08ebaedad7e9c
Signed-off-by: Masereel Pierre <pim@odoo.com>
Signed-off-by: Joseph Caburnay (jcb) <jcb@odoo.com>

addons/point_of_sale/static/src/js/models.js

@@ -1718,7 +1718,7 @@ class Orderline extends PosModel {
         // 1) Flatten the taxes.
 
         var _collect_taxes = function(taxes, all_taxes){
-            taxes.sort(function (tax1, tax2) {
+            taxes = [...taxes].sort(function (tax1, tax2) {
                 return tax1.sequence - tax2.sequence;
             });
             _(taxes).each(function(tax){