[FIX] sale_project,sale_timesheet: display Sale Order button w/o need for Billable

Previously, the button Sale Order in a Project form could only be seen when the sale_timesheet module (installed automatically with the Timesheet, Sales and Project apps) is installed.
Now, only the Sales and Project apps are needed to be able to display the Sale Order button.

opw-2530161

closes odoo/odoo#73239

Signed-off-by: Simon Goffin (sig) <sig@openerp.com>