Create DB: fix local 'updated' timestamp

In some cases, the local timestamp was not updated and set to default
0000-00-00 00:00:00 instead of the current time.
Create DB: change column order in v_exp_membres

Display date_modif before erreurs
Update: revise query to include rows with errors

Prior to this, the process only updated rows that had been changed
locally after import.

With this change, rows that generated errors during validation are
systematically included to ensure that Mailchimp is updated with the
latest error messages.
Minor code reformatting
Update: fix bug when updating only 'erreurs'

When updating a Mailchimp record where only the 'erreurs' field was
changed, the groupings were overwritten (all items unset).

This commit adds a parameter to the ProcessGroupings() function, to
force the generation of the groupings when any field has been updated
to avoid such occurence.
Update: improve query to exclude rows with identical errors
Update: improve performance

Only connect to Mailchimp when we have data to update.
Create DB: update comment
Create DB: Add ecole to v_exp_classes
Create DB: new view v_exp_news_coet

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