Drawer notifications need to leverage the severity we're introducing in RHCLOUD-41535.

Since the Drawer is not GA yet, we don't need to use beta templates for this ticket.

Acceptance criteria:

• Templates from the engine module MUST NOT be updated.
• Talk with UXD/PM first as no guidance has been provided yet about the severity in Drawer templates.
• All drawer templates include the severity when available (it is optional in the action schema).
• Unit tests are updated.