[ADD] account_statement_import_txt_xlsx: show mapping error

If there is a problem parsing the file we are not showing the error
to the user, instead a generic message telling something is wrong
with the type of file is shown, and we only showing the error if
we are running unit tests.

In this case we think is good to show the error to the user, this
way they can check what is wrong and fix it in the sheet mapping.

* We are only showing the title of the error as a HINT, we think that is
  a good start to undestand what needs to change in the sheet mapping.
* The complete traceback error is shown in the log if we needed for more
  detail review from the technical teams.

account_statement_import_txt_xlsx/models/account_statement_import.py

@@ -3,7 +3,8 @@
 
 import logging
 
-from odoo import fields, models
+from odoo import _, fields, models
+from odoo.exceptions import UserError
 
 _logger = logging.getLogger(__name__)
 
@@ -32,10 +33,11 @@ class AccountStatementImport(models.TransientModel):
                 return Parser.parse(
                     data_file, self.sheet_mapping_id, self.statement_filename
                 )
-            except BaseException:
+            except BaseException as exc:
                 if self.env.context.get("account_statement_import_txt_xlsx_test"):
                     raise
                 _logger.warning("Sheet parser error", exc_info=True)
+                raise UserError(_("Bad file/mapping: ") + str(exc)) from exc
         return super()._parse_file(data_file)
 
     def _create_bank_statements(self, stmts_vals, result):