Adding the DAO layer for vpp user management

fixes https://roadmap.entgra.net/issues/10169

+                long currentTime = System.currentTimeMillis();
+                stmt.setString(1, userDTO.getClientUserId());
+                stmt.setString(2, userDTO.getDmUsername());
+                stmt.setInt(3, userDTO.getTenantId());

+package io.entgra.device.mgt.core.application.mgt.core.dao;

+                + "MANAGED_ID, "
+                + "TEMP_PASSWORD "
+                + "FROM AP_VPP_USER "
+                + "WHERE DM_USERNAME = ?";