[REM][MOV] knowledge: move to enterprise

Due to business decisions knowledge is moved to enterprise repository. As
some other moves are planned, notably coupon or the complete responsible UI
and support that are coming to community Odoo feels like knowledge belongs
to enterprise applications.

Planned move from enterprise to community are

  * mass mailing themes;
  * mobile UI;
  * complete coupon and loyalty cards support;
  * spreadsheet library;

For any questions please refer to decision makers.

Task-2900765

X-original-commit: 9ba76621dc66fcf672ce514a47cc933bd9462f38
Part-of: odoo/odoo#95556