Disabled LAContext attribute in simulator [SDK-1476]

[Widcket]

Changes

The iOS 13.4 simulator seems to have introduced a bug in the behavior of SecItemCopyMatching when a LAContext instance is used in the query.

Using any key will result in a successful OSCode:

let laContext = LAContext()

let loadQuery = [
  kSecClass as String: kSecClassGenericPassword,
  kSecAttrService as String: UUID().uuidString,
  kSecUseAuthenticationContext as String: laContext // 👈🏻
] as [String : Any]

let result = SecItemCopyMatching(loadQuery as CFDictionary, nil)
print("Result: \(result == errSecSuccess)")

// Result: true

And no data will actually be retrieved:

let laContext = LAContext()
let key = "foo"

let saveQuery = [
    kSecClass as String: kSecClassGenericPassword,
    kSecAttrService as String: key,
    kSecValueData as String: "bar".data(using: .utf8)!,
    kSecUseAuthenticationContext as String: laContext // 👈🏻
] as [String : Any]

SecItemAdd(saveQuery as CFDictionary, nil)

let loadQuery = [
    kSecClass as String: kSecClassGenericPassword,
    kSecAttrService as String: key,
    kSecReturnData as String: kCFBooleanTrue!,
    kSecUseAuthenticationContext as String: laContext // 👈🏻
] as [String : Any]

var dataTypeRef: CFTypeRef?
SecItemCopyMatching(loadQuery as CFDictionary, &dataTypeRef)

print(String(data: (dataTypeRef as? Data) ?? "nope!".data(using: .utf8)!, encoding: .utf8)!)

// nope!

This PR disables the use of kSecUseAuthenticationContext in simulator targets.

References

Fixes #90

Testing

[ ] This change adds unit test coverage (or why not)
[X] This change has been tested on the latest version of the platform/language or why not

Checklist

[X] I have read the Auth0 general contribution guidelines
[X] I have read the Auth0 Code of Conduct
[ ] All existing and new tests complete without errors