[FIX] stock: modal buttons spacing

=== BEFORE ===

Buttons inside the modal were missing a gap in-between. There are also
two other buttons on the right side of the modal but these don't need a
gap because they have no background.

=== AFTER ===

We add a combination of `d-flex` and `gap-1` class to space the button
consistently with other modules

task-3389116
part of task-3326263

closes odoo/odoo#127153

X-original-commit: e1a3d599acafe55bd4b432bf9495ebbd4eee33c7
Signed-off-by: Pierre Paridans (app) <app@odoo.com>

addons/stock/views/stock_move_views.xml

@@ -181,7 +181,7 @@
                            context="{'tree_view_ref': 'stock.view_stock_move_line_operation_tree', 'default_product_uom_id': product_uom, 'default_picking_id': picking_id, 'default_move_id': id, 'default_product_id': product_id, 'default_location_id': location_id, 'default_location_dest_id': location_dest_id, 'default_company_id': company_id}"
                            widget="sml_x2_many"/>
                     <footer class="d-flex justify-content-between" attrs="{'invisible': ['|', ('state', '=', 'cancel'), '&amp;', ('state', '=', 'done'), ('is_locked', '=', True)]}">
-                        <div>
+                        <div class="d-flex gap-1">
                             <button string="Confirm" special="save" data-hotkey="v" class="oe_highlight"/>
                             <button string="Discard" special="cancel" data-hotkey="z"/>
                         </div>