feat: implement send/receive custom buffer

…no root privileagues

…code

…essage handler

…er task handler

… the server-side request error (missing Copy trait)

…ature

…ount in and out parameter

…tests to the new logic

…t behavior

…ral purpose CFC handler

…stom server example

…response

…des when sending a CFC request

…ation

…ssage

… found

…d CFC is found"

This reverts commit d91ec3f.

…st in message"

This reverts commit 14e6134.

…mplementation"

This reverts commit 2d1ccab.

…ction codes when sending a CFC request"

This reverts commit afbfbca.

… arms

…o 255

Feat: Improvement of the Custom Function Code Feature (CFC)