GH-4071 Heavily refactor and rearchitect account system

This makes the account system much more modular
and makes it treat errors as something recoverable,
unless they come directly from the MSA refresh token
becoming invalid.

launcher/ui/widgets/ErrorFrame.h

@@ -0,0 +1,49 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QFrame>
+
+namespace Ui
+{
+class ErrorFrame;
+}
+
+class ErrorFrame : public QFrame
+{
+    Q_OBJECT
+
+public:
+    explicit ErrorFrame(QWidget *parent = 0);
+    ~ErrorFrame();
+
+    void setTitle(QString text);
+    void setDescription(QString text);
+
+    void clear();
+
+public slots:
+    void ellipsisHandler(const QString& link );
+    void boxClosed(int result);
+
+private:
+    void updateHiddenState();
+
+private:
+    Ui::ErrorFrame *ui;
+    QString desc;
+    class QMessageBox * currentBox = nullptr;
+};