Draft: Refactored Csma Module for NetAnim (Updated Approach)

This Merge Request is after implementing @pdbj 's and @tomhenderson's suggestions in !1523. If this approach is okay with everyone and finalized a separate MR will be created to add the proxy.h to the core module. The same approach will be taken for the remaining modules as well.

The second.cc script can be used to check if the refactor was successful.