EMail Verification for new User Accounts

[PaulGoldschmidt]

Problem

Currently, there is no verification for new user accounts and if the entered email address is correct.

Solution

Send out an verification email for address verification.

Additional context

This is also an issue in SpeziFirebase.

Code of Conduct

• I agree to follow this project's Code of Conduct and Contributing Guidelines

[PSchmiedmayer]

Linking this issue to StanfordSpezi/SpeziFirebase#58 on the client side 👍