Show info banner 'E-Mail not verified' in App

[PaulGoldschmidt]

Description

To support #110 and make email notifications feasible, we should make sure users know that there is the option to verify their email.

Reproduction

N/A

Expected behavior

Show an Info "Please Verify your EMail", firebase provides with isEmailVerified(). We should take a look at how Spezi-Firebase and Spezi-Account handles this, too.

Additional context

No response

Code of Conduct

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