This commit fixes a couple of issues linked to relational fields:
- When previewing a file with relational fields/ids, they were not
correctly mapped to their respective fields in the selects, the fields
were also not correctly mapped in the arguments given for the import.
- The select label was also only showing the name of the last sub-field
while it should show the full path ("External ID" vs "Company / External
ID").
- Some errors were not correctly displayed: wrong field name, not in a
column when it should be.
Task ID: 3210337
opw-3203704 + opw-3192403
closesodoo/odoo#114490
X-original-commit: 871690afdc2ce4da2770a144cc4fc5ed038e6f73
Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>