First seen date can be more recent than last seen date

[amr-cossi]

Description

It is possible to have a first seen date more recent than a last seen date, which is incoherent and could cause problems in visualizing and exporting data.

Reproducible Steps

Steps to create the smallest reproducible scenario:

1. Create a new relation between two entites.
2. Put a first seen date more recent than a last seen date : for instance, first seen : 12/02/2020 ; last seen 01/01/2010
3. Close the window

Expected Output

A message of error should appear.

Actual Output

The relation with the first seen more recent than the last seen can be created.