host_init_verifier: use libhidlmetadata

Since it's available in C++, it's easier to build host_init_verifier
with this than create a new way to export the json file.

Bug: 141567104
Test: manually change hidl interface in a manifest
host_init_verifier: system/core/rootdir/init.rc: 69:
host_init_verifier: Interface is not in the known set of hidl_interfaces: 'android.hardwar.edne@1.0::IFoo'. Please ensure the interface is spelled correctly and built by a hidl_interface target.
Change-Id: Ic73dcb51855cb751734bc497d8e69f379966c511