Revert "Remove c++ implementation of aconfigd" am: 42c46ee4dd

Original change: https://android-review.googlesource.com/c/platform/system/server_configurable_flags/+/3454581

Change-Id: Icea2b4f874831af554035b6630a3ea210bebd453
Signed-off-by: Automerger Merge Worker <[email protected]>