update email provider to create user

Author: russellwheatley

FirebaseSwiftUI/FirebaseAuthSwiftUI/Sources/FirebaseAuthSwiftUI/Services/EmailProvider.swift

@@ -10,14 +10,8 @@ public class EmailAuthProvider {
   }
 
   func signIn(withEmail email: String, password: String) async throws {
-    authEnvironment.authenticationState = .authenticating
-    do {
-      try await authEnvironment.auth.signIn(withEmail: email, password: password)
-      authEnvironment.updateAuthenticationState()
-    } catch {
-      authEnvironment.authenticationState = .unauthenticated
-      throw error
-    }
+    let credential = FirebaseAuth.EmailAuthProvider.credential(withEmail: email, password: password)
+    try await authEnvironment.signIn(with: credential)
   }
 
   func createUser(withEmail email: String, password: String) async throws {