[MERGE][ADD] project_expense: setting project on expense

This merge commit provide the possibility for project user to select
a project on an expense. Selectable project are only the one with an
analytic account set. Setting the project will set the analytic
account, so posting the expense will create analytic entries, and will
finally appear on the project overview.
If the analytic account still match an open sale order (and if the
product is reinvoicable), a new SO line will be added on the SO (this
flow does not change here).

Task-1843241 (previsouly Task-1911581)

closes odoo/odoo#29638

Signed-off-by: Jérome Maes (jem) <jem@openerp.com>