[IMP] hr_payroll_account: Avoiding creating empty journal entries

Purpose
=======

Steps to reproduce
------------------

Install hr_payroll_account
Configure a salary rule
Create a payslip and confirm

Current behavior
----------------

A journal entry is created without items.

Expected behavior
-----------------

Create the journal entry with all items like it's created
When the payslip is computed (compute sheet button) and validated.

resolve https://github.com/odoo/odoo/issues/24796

Specification
=============

Now the super of ```action_payslip_done``` is called before the creation
of the journal entry. This means that the ```compute_sheet``` method is
called too before the filling of the account move.

addons/hr_payroll_account/models/hr_payroll_account.py

@@ -53,6 +53,7 @@ class HrPayslip(models.Model):
 
     @api.multi
     def action_payslip_done(self):
+        res = super(HrPayslip, self).action_payslip_done()
         precision = self.env['decimal.precision'].precision_get('Payroll')
 
         for slip in self:
@@ -138,7 +139,7 @@ class HrPayslip(models.Model):
             move = self.env['account.move'].create(move_dict)
             slip.write({'move_id': move.id, 'date': date})
             move.post()
-        return super(HrPayslip, self).action_payslip_done()
+        return res
 
 
 class HrSalaryRule(models.Model):