This change mechanically copies
runtime/tests/vm/dart -> runtime/tests/vm/dart_2
in preparation for the migration of runtime/tests/vm/dart to NNBD.
Corresponding statuses in vm.status are duplicated.
Added vm_nnbd builder tag for NNBD bots.
vm/dart/* tests are allowed to run only on vm_nnbd builders.
vm/dart_2/* tests are allowed to run only on non-vm_nnbd builders.
Issue: https://github.com/dart-lang/sdk/issues/41314
Change-Id: I079da92da17960605f37c1c0e28e48362b236739
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149485
Reviewed-by: Régis Crelier <regis@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>