Add use_app_image_startup_cache feature flag

Passed down to the zygote if the corresponding system property is set:
runtime_native / use_app_image_startup_cache.

Bug: 123524494
Bug: 116059983
Test: adb shell device_config put runtime_native use_app_image_startup_cache true

Change-Id: I27c0b9ea9533b2b6ad1ccd45f0fb9292c4cfca02