[ADD] web_tip: module for tip generation

This PR adds the web_tip module. 

Tips are now displayed when specific conditions are met.

The module also allows other modules to define their own tips. Included in this PR are tip definitions for the CRM module.


task: https://www.odoo.com/web#id=8829&view_type=form&model=project.task&menu_id=3942&action=327