[roll] Roll fuchsia [build] Validate structured config in fuchsia_package().

By default, all fuchsia_packages() will ensure they have config
provided at build-time. If they need to have configuration provided
during assembly-time, they will need to disable the check and rely
on the product assembly tool's validation pass which covers
all packages in a system image but does not run during many edit/test
workflows and does not apply to packages in the universe set.

This requires changing the "root" target emitted by fuchsia_package()
from pm_build() to a group() which deps on the pm_build() target and
optionally on the new validate_packaged_config() target.

Adds an argument to pm_build() to allow fuchsia_package() to keep
existing package out directory paths the same while changing the
target name used for pm_build() inside fuchsia_package().

Updates the vulkan-validation-pkg build to determine the path to
meta.far.merkle by inferring target_out_dir from the target name and
constructing an explicit subpath, rather than querying the pm_build()
target for its outputs. It is no longer possible to call
get_target_outputs() on the label of a fuchsia_package() target, because
groups cannot be queried for their outputs.

Updates deprecated_dart_app_allowlist and deprecated_flutter_app_allowlist
to include the additional target emitted by fuchsia_package().

Original-Fixed: 93345
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/666545
Original-Revision: ec7ef5e86d5894acb9b95b370dc3917b99c37ec7
GitOrigin-RevId: ab00e4812ba004b63ee0d112e7790185e744e2f2
Change-Id: I78f1bae87ebb5fce5a1a9c52d6bbef247ff652bc