Propagate hiddenapi cmdline flags in OatFileAssistant::Dex2Oat

ART can invoke dex2oat on an out-of-date or non-existent oat file.
This code path will ignore any runtime hidden API enforcement policy
settings. Change the code to set the correct flag and add a gtest
for it.

Bug: 79680013
Test: make test-art-host-gtest-oat_file_assistant_test
Change-Id: Id6aa5e45d11626facb590621d43e2c52b9269b12