French PDP registration now validates the company SIREN more carefully instead of assuming the first nine characters are correct. This reduces incorrect business identification data being sent during KYC and related flows, especially when users enter a company name instead of a valid number.

Currently we just take the first 9 numbers of the `company_id` and say it is the SIREN.

On IAP we have some people who just seem to have put their company name.

After this commit we use a helper method that does some simple validation at least.

task-None

Forward-Port-Of: odoo/odoo#268621
Forward-Port-Of: odoo/odoo#268202

Corrected how notes are written in French PDP electronic invoice messages so their content appears in the expected place. This helps ensure affected messages meet the required format and reduces the risk of processing or compliance issues.

'Content' was set as an attribute of 'IncludedNote' instead of a child node.

See ppf messages 164, 166 & 168

Forward-Port-Of: odoo/odoo#268593