bgpd, lib: Remove RESTRICTED_NODE from code base

bgpd, lib: Remove RESTRICTED_NODE from code base

The RESTRICTED_NODE command is not used, introduces code
complexity and provides no additional levels of security.

The only way to get into RESTRICTED_NODE is to add, under
vty configuration the command 'anonymous restricted', and
then telnet to a daemon, provide a password, then type
'enable' and fail to enter the password three times.
Then the user can enter a very limited set of commands to
monitor bgp and only bgp behavior.

This commit removes both the RESTRICTED_NODE usage as well
as the lib/* usage of the code

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>