packaging: setup: reorg the per component directory

no reason to have cryptic names within hierarchy.

engine_common/enginecommonconfig.py.in -> engine_common/config.py.in
engine_common/enginecommonconstants.py -> engine_common/constants.py
engine/engineconfig.py.in -> engine/config.py.in
engine/engineconstants.py -> engine/constants.py

Change-Id: I2f044b4c6170083337d051eafeba8c623faed845
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>