Enable the display of the broadcast card on the grades page

[camillebrulotte]

Is your feature request related to a problem? Please describe.
Users don't necessarily read or notice messages on the dashboard, so if the message is right under their eyes on the notes page, there is a higher chance that they will be aware that the grades are not displayed because it's the evaluation period.

Describe the solution you'd like
Enable the display of the broadcast card on the grades page, with a flag in Firebase that determines whether it appears on the dashboard page OR the grades page.