IF update - 9: logical interface API update

Updated the #external #access #API for #logical #interface framework in IF module. The #create / #query / #remove routines has been #upgraded for the new data-structure changes. The agent traversal routines also has been updated according to the new indexing.

#IF update 9 ...
[commit e4ab9bfdfeec94d39887b6739d42862b47e82782] (https://github.com/nes-repo/NES-Open-Switch/commit/e4ab9bfdfeec94d39887b6739d42862b47e82782)