Install prebuilt_etc modules to out/soong

prebuilt_etc* modules emit build rules to install their output to
out/soong. This is required for the cvd_host_package module to gather
installed files (not built files) of prebuilt_etc* modules.

Bug: 168086242
Test: m

Change-Id: I065640c7e6f188b0c19e70f081e82bdc30d7e752