Handle when serviceId is not present and store serviceId in keychain

[Supereg]

Handle when serviceId is not present and store serviceId in keychain

♻️ Current situation & Problem

Currently, there is an issue when running a reinstalled application where the firebase credentials where previously stored in the keychain that we don't have a reference to the previous serviceId as this is stored in localStorage.
This PR addresses this issue by (1) gracefully handling the error and (2) storing the server id in the keychain as well to have similar persistence as the firebase key.

⚙️ Release Notes

• Fixed an issue where it was impossible to log back in when an app was deleted with a signed in user.

📚 Documentation

✅ Testing

📝 Code of Conduct & Contributing Guidelines

By submitting creating this pull request, you agree to follow our Code of Conduct and Contributing Guidelines:

• I agree to follow the Code of Conduct and Contributing Guidelines.

[PSchmiedmayer]

Thank you for the improvements and discussion in the office @Supereg; looks great 👍

[codecov]

Codecov Report

Attention: Patch coverage is 90.24390% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 60.80%. Comparing base (ca1edf6) to head (b139544).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #28      +/-   ##
==========================================
+ Coverage   60.04%   60.80%   +0.77%     
==========================================
  Files          19       19              
  Lines        1071     1102      +31     
==========================================
+ Hits          643      670      +27     
- Misses        428      432       +4     

Files	Coverage Δ
...aseAccount/FirebaseAuthAuthenticationMethods.swift	100.00% <ø> (ø)
.../SpeziFirebaseAccount/Models/FirebaseContext.swift	91.18% <90.25%> (-0.61%)	⬇️

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