Move sysprop assignments to separate mk file

core/sysprop_config.mk is added to separate code setting
ADDITIONAL_*_PROPERTIES variables. This should be a no-op for now but it
will help migrate build.prop generation to Soong.

Bug: 322090587
Test: compare build.prop files before and after
Change-Id: I57a1ae899865027bcadddc2071fcd2afcf2703bc