[FIX] stock_account: inventory valuation value in company currency

In multicompany,
Have company B with a different currency than company A
With a shared product catalog
Open the inventory valuation report for company B

Before this commit the stock Value is expressed in company A's currency,
even though the value itself is correct

After this commit, the stock value is expressed in the right currency

OPW 1912511

closes odoo/odoo#30242

addons/stock_account/models/product.py

@@ -101,6 +101,7 @@ class ProductTemplate(models.Model):
 class ProductProduct(models.Model):
     _inherit = 'product.product'
 
+    stock_value_currency_id = fields.Many2one('res.currency', compute='_compute_stock_value_currency')
     stock_value = fields.Float(
         'Value', compute='_compute_stock_value')
     qty_at_date = fields.Float(
@@ -176,6 +177,12 @@ class ProductProduct(models.Model):
         moves = StockMove.search(domain)
         return sum(moves.mapped('remaining_value')), moves
 
+    @api.multi
+    def _compute_stock_value_currency(self):
+        currency_id = self.env.user.company_id.currency_id
+        for product in self:
+            product.stock_value_currency_id = currency_id
+
     @api.multi
     @api.depends('stock_move_ids.product_qty', 'stock_move_ids.state', 'stock_move_ids.remaining_value', 'product_tmpl_id.cost_method', 'product_tmpl_id.standard_price', 'product_tmpl_id.property_valuation', 'product_tmpl_id.categ_id.property_valuation')
     def _compute_stock_value(self):

addons/stock_account/views/stock_account_views.xml

@@ -77,7 +77,8 @@
                     <field name="qty_at_date"/>
                     <field name="uom_id" groups="uom.group_uom"/>
                     <field name="currency_id" invisible="1"/>
-                    <field name="stock_value" sum="Stock Valuation" widget="monetary"/>
+                    <field name="stock_value_currency_id" invisible="1"/>
+                    <field name="stock_value" sum="Stock Valuation" widget="monetary" options="{'currency_field': 'stock_value_currency_id'}"/>
                     <field name="cost_method" invisible="1"/>
                     <button name="action_valuation_at_date_details" type="object" icon="fa-info-circle" aria-label="Valuation" title="Valuation" attrs="{'invisible': [('cost_method', '!=', 'fifo')]}" />
                 </tree>