fix: add missing hook in propal and invoice (contact and document tabs)

[FHenry]

• htdocs/comm/propal/contact.php hookmanager is corrrectly implemented (with doAction) in 19.0. I suggest to add only $hookmanger->init in 18.0 (to at least be able use llxfooter hook).
• compta/facture/contact.php hookmanager is corrrectly implemented (with doAction) in 19.0. I suggest to add only $hookmanger->init in 18.0 (to at least be able use llxfooter hook).
• htdocs/comm/propal/document.php hookmanager->init is missing even in newer version, implement the same way as it's already done in htdocs/commande/document.php
• htdocs/compta/facture/document.php hookmanager->init is missing even in newer version, implement the same way as it's already done in htdocs/commande/document.php