Allow OatFileAssistant::Create to take std::nullopt for the context.

Partially cherry picked from
commit 12f45c41158de6f6737efb102161f86f462d9290.

Bug: 249984283
Test: m test-art-host-gtest-art_runtime_tests
Change-Id: I7ebe2aa745d0da31242034a27f92b24dbdb08740
Merged-In: I7ebe2aa745d0da31242034a27f92b24dbdb08740
4 files changed