[IMP] hr_recruitment: add new digest tips

PURPOSE

Review the tips and digest layout design to make sure they have a WOW effect
and increase trial conversion/retention.

SPECIFICATIO

“Let candidates apply by email”

See code for specifications.

LINKS

Task ID-2274264
COM PR: odoo/odoo#53580
ENT PR: odoo/enterprise#1139

X-original-commit: 5c6c52a8773b1994c9616900d9736cea500776fd