Adding support for Sign In with Apple

[Supereg]

Adding support for Sign In with Apple

♻️ Current situation & Problem

Currently, we only support email- and password-based authentication using Firebase. This PR makes the first step to add single sign on providers by adding support for Sign in with Apple.

⚙️ Release Notes

• Add support for Sign In with Apple

📚 Documentation

Documentation was adjusted were required.

✅ Testing

Testing was added where possible. As we cannot rely reliably test Sign in with Apple, the Firebase Identity Provider Account Service is not fully tested autonomously.

📝 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.

[codecov]

Codecov Report

Merging #18 (b87cb0e) into main (56dd7fb) will decrease coverage by 3.26%.
The diff coverage is 68.46%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #18      +/-   ##
==========================================
- Coverage   62.41%   59.14%   -3.26%     
==========================================
  Files          10       17       +7     
  Lines         641     1023     +382     
==========================================
+ Hits          400      605     +205     
- Misses        241      418     +177     

Files	Coverage Δ
...count/AccountValues/FirebaseEmailVerifiedKey.swift	0.00% <ø> (ø)
...FirebaseAccount/FirebaseAccountConfiguration.swift	100.00% <100.00%> (ø)
...aseAccount/FirebaseAuthAuthenticationMethods.swift	100.00% <ø> (ø)
...urces/SpeziFirebaseAccount/Utils/CryptoUtils.swift	95.00% <95.00%> (ø)
...ccount/Account Services/FirebaseAccountError.swift	67.11% <50.00%> (ø)
...irebaseAccount/Views/FirebaseAccountModifier.swift	90.91% <90.91%> (ø)
...eAccount/Views/FirebaseSignInWithAppleButton.swift	70.38% <70.38%> (ø)
...Services/FirebaseEmailPasswordAccountService.swift	90.39% <90.39%> (ø)
...ount/Account Services/FirebaseAccountService.swift	79.27% <79.27%> (ø)
...s/SpeziFirebaseAccount/Utils/FirebaseContext.swift	91.99% <91.99%> (ø)
... and 2 more

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[PSchmiedmayer]

Thank you, looks great as discussed in the meeting!