KeyMint VTS: Use a strongbox must support DIGEST for importKey

"ImportWrappedKeyTest.WrongDigest" tried to wrap a keyBlob by one digest
type and unwrap it by another digest type.

It's been OK for KeyMint implementations to allow unsupported
parameters/characteristics at key generation time, and only police their
use, at begin() time. However if an implementation wants to secure it at
the key generation/importing time the first digest type must be
supported by all implementation.

Bug: 249276913
Test: VtsAidlKeyMintTargetTest
Change-Id: I6bc000026e9e4aec0aa82078a98c75e2d7c56847