[VM] Resolve package config (absolute) uri in kernel service
[VM] Resolve package config (absolute) uri in kernel service

Response to https://buganizer.corp.google.com/issues/237271829

TEST=Existing tests --- test specifically for this will come later.

Change-Id: Ife30492f222e6bdb56fc5f89da291a1cfebd48d0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/250040
Reviewed-by: Martin Kustermann <a35dd5b79fac84b2bb3b026a16b8becc55af5961@google.com>
Commit-Queue: Jens Johansen <05223a3c6bdf76af6f84755eae231abeebcf4530@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk