In this PR we make several UX changes that should make the life of the user easier: - Add the possibility to upload personal documents in the contract - Fine tuning of some fields (control of exclusive fields, conditional appearing of certain fields to not overcharge the display) - Improve the order of tabs and their layout task-3069359 closes odoo/odoo#122116 Related: odoo/enterprise#39804 Signed-off-by: Sofie Gvaladze (sgv) <sgv@odoo.com>