MXS-1467: Create csmon

Added the csmon monitor which supports both old and new ColumnStore
servers. As older server versions aren't able to express their role, the
master needs to be designated by the user. When a ColumnStore version is
released that supports the mcsSystemPrimary() function, the master can be
automatically found.

server/modules/monitor/csmon/csmon.hh

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2018 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2022-01-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+#pragma once
+
+#include <maxscale/ccdefs.hh>
+#include <maxscale/monitor.hh>
+
+class CsMonitor : public maxscale::MonitorInstanceSimple
+{
+public:
+    CsMonitor(const CsMonitor&) = delete;
+    CsMonitor& operator=(const CsMonitor&) = delete;
+
+    ~CsMonitor();
+    static CsMonitor* create(MXS_MONITOR* monitor);
+
+protected:
+    bool has_sufficient_permissions() const;
+    void update_server_status(MXS_MONITORED_SERVER* monitored_server);
+
+private:
+    CsMonitor(MXS_MONITOR* monitor);
+
+    SERVER* m_primary;
+};