Merge "Move env var config loading to be within the config package." am:...

Merge "Move env var config loading to be within the config package." am: 5ddefa3d am: 15747009 am: 9cd2b998 am: 601852b3

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/1961101

Change-Id: Icd7a8132eeed34ccb1d4dc974a23dd8c87768900