wic: direct_plugin: stop using config manager

wic: direct_plugin: stop using config manager

This is a preparation to removing conf.py and config/wic.conf
from the codebase.

Got rid of using configmgr global object in direct_plugin and direct
modules. It was used to implicitly parse kickstart file and set
couple of variables.

Replaced usage of configmgr by passing parameters directly to the
DirectImageCreator.

[YOCTO #10619]

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>