[PM-3382] User cannot select Email as a secondary 2FA option following SSO (#2719)

* [PM-3382] Update mobile client to receive and use SsoEmail2faSessionToken

* [PM-3382] Fix null 2fa email with local email on MP login.

src/Core/Models/Request/TwoFactorEmailRequest.cs

@@ -5,5 +5,6 @@
         public string Email { get; set; }
         public string MasterPasswordHash { get; set; }
         public string DeviceIdentifier { get; set; }
+        public string SsoEmail2FaSessionToken { get; set; }
     }
 }

src/Core/Models/Response/IdentityTwoFactorResponse.cs

@@ -12,5 +12,7 @@ namespace Bit.Core.Models.Response
         public MasterPasswordPolicyOptions MasterPasswordPolicy { get; set; }
         [JsonProperty("CaptchaBypassToken")]
         public string CaptchaToken { get; set; }
+        public string SsoEmail2faSessionToken { get; set; }
+        public string Email { get; set; }
     }
 }