Allow skipping multple remotes via management interface

Allow skipping multple remotes via management interface

The mamangement command "remote SKIP" is extended with an
optional parameter 'count' > 0. If count is greater than
number of connection entries (len), count % len is used.
On going past the index of the last connection entry,
counting is restarted from the first connection entry.

Without this, use of management-query-remote from a UI is
virtually impractical except when there are only a handful
of remote entries. Skipping the entries one by one takes
a long time when there are many entries to be skipped
(~ 1 second per entry).  Use of "remote MOD" is not an
option as change of protocol is not supported.

Management clients can determine the availability of this
feature by checking that the management interface version
is > 3. Older versions will ignore the count parameter and
behave identically to using count = 1.

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <20210907223614.8574-1-selva.nair@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg22817.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit ec5ffe35a394c44b1ea25b7c10dab7da7d792ef2)