[ADD] add `project_timesheet_funding_wish` addon

adds in the timesheet lines:
- ``funding wish`` field: user tells if we want to be paid for the
time spent
- ``treated`` field: tells if the timesheet line has been considered
in internal invoicing process

Task: JOI-13

project_timesheet_funding_wish/i18n/README

@@ -0,0 +1 @@
+This directory should contain the *.po for Odoo translation.