Implement 'shell pm path' to display APEX source path

The change is mainly for developement purpose
Currently 'shell pm path $APEX_PKG_NAME' can not disply source path
It is make sense that 'shell pm path $APEX_PKG_NAME' show path

Fixes: 142115351
Test: adb shell pm path $APEX_PKG_NAME
Test: adb shell pm path $APK_PKG_NAME
Change-Id: Ifd7297b6dbd8c684a7f8375c4d6671976f12da60