[FIX] base_comment_template: Incorrect m2m column names + script + avoid FK constraint

- The name of the columns were swapped, so better to fix it for avoiding
  mistakes due to this.
- Migration script for detecting the condition and swap column names.
- On v12 > v13 migration, include JOINs for avoiding FK constraint,
  which `ON CONFLICT` clause doesn't protect.

base_comment_template/models/res_partner.py

@@ -11,8 +11,8 @@ class ResPartner(models.Model):
     base_comment_template_ids = fields.Many2many(
         comodel_name="base.comment.template",
         relation="base_comment_template_res_partner_rel",
-        column1="base_comment_template_id",
-        column2="res_partner_id",
+        column1="res_partner_id",
+        column2="base_comment_template_id",
         string="Comment Templates",
         help="Specific partner comments that can be included in reports",
     )