Custom Benchmark Errors and Override (#9517)

* initial idea

* update benchmark test to frame v2

* fix some errors

* fixes for elec phrag

* fix tests

* update extrinsic time and docs

* fix import

* undo extra changes

* helper function

* wrong way

* Update frame/benchmarking/src/utils.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* doesnt need encode/decode

* fix benchmark return

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>