Check app-attest-key feature supported while using ATTEST_KEY in tests.

Adding a check to skip the attest-key tests if
`android.hardware.keystore.app_attest_key` feature is not enabled.

Bug: 363867143
Test: atest keystore_client_tests
Change-Id: I4ef356b1924914bd7318b293e0b4bf3b1da55b59
1 file changed