WebService: Verify username and token (#2930)

* WebService: Verify username and token; Log errors in PostJson

* Fixup: added docstrings to the functions

* Webservice: Added Icons to the verification, imrpved error detection in cpr, fixup nits

* fixup: fmt warning

src/core/telemetry_session.h

@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <future>
 #include <memory>
 #include "common/telemetry.h"
 
@@ -47,4 +48,13 @@ u64 GetTelemetryId();
  */
 u64 RegenerateTelemetryId();
 
+/**
+ * Verifies the username and token.
+ * @param username Citra username to use for authentication.
+ * @param token Citra token to use for authentication.
+ * @param func A function that gets exectued when the verification is finished
+ * @returns Future with bool indicating whether the verification succeeded
+ */
+std::future<bool> VerifyLogin(std::string username, std::string token, std::function<void()> func);
+
 } // namespace Core