Add supported PackageInfo to ExplicitHealthCheckService API

With the change in I4f13638598037acaeb30d61c8d5178f45882fcba
to separate the PackageWatchdog package expiry deadline from the explicit
health check deadline. It would be cleaner for ExtServices to supply
this deadline per-package. We now do that as a field in
PackageInfo.

Bug: 120598832
Test: Builds

Change-Id: I29e2d619a5296716c29893ab3aa2f35f69bfb4d7