[FIX] analytic invoice/contract lines inheritance

Bug description
---------------

`account.analytic.contract.line` inherits
`account.analytic.invoice.line`

`account.analytic.invoice.line` defines field `analytic_account_id`:
   - comodel='account.analytic.account'

`account.analytic.contract.line` redefines field `analytic_account_id`:
   - comodel='account.analytic.contract'

On attempt to extend `account.analytic.invoice.line` model adding
field that depends on `analytic_account_id.date_start`
Odoo fails to update, because it adds this field to
`account.analytic.contract.line` through inheritance,
and `account.analytic.contract` model have no this field.

What is done
------------

Change inheritance order:
- `account.analytic.invoice.line` inherits
`account.analytic.contract.line`
- no file renames at this stage (this wil be done in next commit)

contract/models/account_analytic_contract_line.py

@@ -5,15 +5,13 @@
 from odoo import fields, models
 
 
-class AccountAnalyticContractLine(models.Model):
-
-    _name = 'account.analytic.contract.line'
-    _description = 'Contract Lines'
-    _inherit = 'account.analytic.invoice.line'
+class AccountAnalyticInvoiceLine(models.Model):
+    _name = 'account.analytic.invoice.line'
+    _inherit = 'account.analytic.contract.line'
 
     analytic_account_id = fields.Many2one(
-        string='Contract',
-        comodel_name='account.analytic.contract',
+        'account.analytic.account',
+        string='Analytic Account',
         required=True,
         ondelete='cascade',
     )

contract/models/account_analytic_invoice_line.py

@@ -12,8 +12,9 @@ from odoo.exceptions import ValidationError
 from odoo.tools.translate import _
 
 
-class AccountAnalyticInvoiceLine(models.Model):
-    _name = 'account.analytic.invoice.line'
+class AccountAnalyticContractLine(models.Model):
+    _name = 'account.analytic.contract.line'
+    _description = 'Contract Lines'
     _order = "sequence,id"
 
     product_id = fields.Many2one(
@@ -22,8 +23,8 @@ class AccountAnalyticInvoiceLine(models.Model):
         required=True,
     )
     analytic_account_id = fields.Many2one(
-        'account.analytic.account',
-        string='Analytic Account',
+        string='Contract',
+        comodel_name='account.analytic.contract',
         required=True,
         ondelete='cascade',
     )

contract_variable_quantity/models/contract.py

@@ -28,8 +28,8 @@ class AccountAnalyticAccount(models.Model):
         return vals
 
 
-class AccountAnalyticInvoiceLine(models.Model):
-    _inherit = 'account.analytic.invoice.line'
+class AccountAnalyticContractLine(models.Model):
+    _inherit = 'account.analytic.contract.line'
 
     qty_type = fields.Selection(
         selection=[