Allow the avatar to be changed

This Merge Request allows an avatar to be set through the userEditSheet
The parts in controller.cpp decode the url and check whether the image
is valid, through qimagereader.

src/controller.cpp

@@ -441,6 +441,22 @@ void Controller::changePassword(Connection *connection, const QString &currentPa
     });
 }
 
+bool Controller::setAvatar(Connection *connection, const QUrl &avatarSource)
+{
+    User *localUser = connection->user();
+    QString decoded = avatarSource.path();
+    if (decoded.isEmpty()) {
+        connection->callApi<SetAvatarUrlJob>(localUser->id(), "");
+        return true;
+    }
+    if (QImageReader(decoded).read().isNull()) {
+        return false;
+    }
+    else {
+        return localUser->setAvatar(decoded);
+    }
+}
+
 NeochatChangePasswordJob::NeochatChangePasswordJob(const QString &newPassword, bool logoutDevices, const Omittable<QJsonObject> &auth)
     : BaseJob(HttpVerb::Post, QStringLiteral("ChangePasswordJob"), QStringLiteral("/_matrix/client/r0") % "/account/password")
 {