frontend: Add frontend applet for ProfileSelect

Responsible for selecting a profile and firing callback upon completion.

src/core/frontend/applets/profile_select.h

@@ -0,0 +1,27 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <functional>
+#include <optional>
+#include "core/hle/service/acc/profile_manager.h"
+
+namespace Core::Frontend {
+
+class ProfileSelectApplet {
+public:
+    virtual ~ProfileSelectApplet();
+
+    virtual void SelectProfile(
+        std::function<void(std::optional<Service::Account::UUID>)> callback) const = 0;
+};
+
+class DefaultProfileSelectApplet final : public ProfileSelectApplet {
+public:
+    void SelectProfile(
+        std::function<void(std::optional<Service::Account::UUID>)> callback) const override;
+};
+
+} // namespace Core::Frontend