core: create qPrefProxy from SettingsObjectWrapper

Update set/get functions to follow common name scheme:
- get function have same name as in struct prefs
- set function have set_<name>
- signal function have <name>_changed

one class one .h/.cpp is the C++ idiom. Having load/sync of each
variable in 1 functions (in contrast to the distributed way
SettingsObjectWrapper handles it) secures the same storage name
is used. Having the set/get/load/sync functions grouped together
makes it easier to get an overview.

REMARK: this commit only defines the class, it is not active in production

Signed-off-by: Jan Iversen <jani@apache.org>

core/settings/qPrefProxy.cpp

@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "qPref.h"
+#include "qPrefPrivate.h"
+
+#include <QNetworkProxy>
+
+static const QString group = QStringLiteral("Network");
+
+qPrefProxy::qPrefProxy(QObject *parent) : QObject(parent)
+{
+}
+qPrefProxy *qPrefProxy::instance()
+{
+	static qPrefProxy *self = new qPrefProxy;
+	return self;
+}
+
+void qPrefProxy::loadSync(bool doSync)
+{
+	disk_proxy_auth(doSync);
+	disk_proxy_host(doSync);
+	disk_proxy_pass(doSync);
+	disk_proxy_port(doSync);
+	disk_proxy_type(doSync);
+	disk_proxy_user(doSync);
+}
+
+HANDLE_PREFERENCE_BOOL(Proxy, "/proxy_auth", proxy_auth);
+
+HANDLE_PREFERENCE_TXT(Proxy, "/proxy_host", proxy_host);
+
+HANDLE_PREFERENCE_TXT(Proxy, "/proxy_pass", proxy_pass);
+
+HANDLE_PREFERENCE_INT(Proxy, "/proxy_port", proxy_port);
+
+HANDLE_PREFERENCE_INT_DEF(Proxy, "/proxy_type", proxy_type, QNetworkProxy::DefaultProxy);
+
+HANDLE_PREFERENCE_TXT(Proxy, "/proxy_user", proxy_user);