Add mainline extension and METADATA.txt to boot.zip.

Contents of METADATA.txt:

booclasspath = dex_bootjars_input/core-oj.jar:dex_bootjars_input/core-libart.jar:dex_bootjars_input/okhttp.jar:dex_bootjars_input/bouncycastle.jar:dex_bootjars_input/apache-xml.jar:dex_bootjars_input/framework.jar:dex_bootjars_input/framework-graphics.jar:dex_bootjars_input/ext.jar:dex_bootjars_input/telephony-common.jar:dex_bootjars_input/voip-common.jar:dex_bootjars_input/ims-common.jar:dex_bootjars_input/core-icu4j.jar:apex_bootjars/framework-adservices.jar:apex_bootjars/framework-sdksandbox.jar:apex_bootjars/framework-appsearch.jar:apex_bootjars/framework-bluetooth.jar:apex_bootjars/conscrypt.jar:apex_bootjars/android.net.ipsec.ike.jar:apex_bootjars/updatable-media.jar:apex_bootjars/framework-mediaprovider.jar:apex_bootjars/framework-ondevicepersonalization.jar:apex_bootjars/framework-statsd.jar:apex_bootjars/framework-permission.jar:apex_bootjars/framework-permission-s.jar:apex_bootjars/framework-scheduling.jar:apex_bootjars/framework-sdkextensions.jar:apex_bootjars/framework-connectivity.jar:apex_bootjars/framework-connectivity-t.jar:apex_bootjars/framework-tethering.jar:apex_bootjars/framework-uwb.jar:apex_bootjars/framework-virtualization.jar:apex_bootjars/framework-wifi.jar
booclasspath-locations = /apex/com.android.art/javalib/core-oj.jar:/apex/com.android.art/javalib/core-libart.jar:/apex/com.android.art/javalib/okhttp.jar:/apex/com.android.art/javalib/bouncycastle.jar:/apex/com.android.art/javalib/apache-xml.jar:/system/framework/framework.jar:/system/framework/framework-graphics.jar:/system/framework/ext.jar:/system/framework/telephony-common.jar:/system/framework/voip-common.jar:/system/framework/ims-common.jar:/apex/com.android.i18n/javalib/core-icu4j.jar:/apex/com.android.adservices/javalib/framework-adservices.jar:/apex/com.android.adservices/javalib/framework-sdksandbox.jar:/apex/com.android.appsearch/javalib/framework-appsearch.jar:/apex/com.android.btservices/javalib/framework-bluetooth.jar:/apex/com.android.conscrypt/javalib/conscrypt.jar:/apex/com.android.ipsec/javalib/android.net.ipsec.ike.jar:/apex/com.android.media/javalib/updatable-media.jar:/apex/com.android.mediaprovider/javalib/framework-mediaprovider.jar:/apex/com.android.ondevicepersonalization/javalib/framework-ondevicepersonalization.jar:/apex/com.android.os.statsd/javalib/framework-statsd.jar:/apex/com.android.permission/javalib/framework-permission.jar:/apex/com.android.permission/javalib/framework-permission-s.jar:/apex/com.android.scheduling/javalib/framework-scheduling.jar:/apex/com.android.sdkext/javalib/framework-sdkextensions.jar:/apex/com.android.tethering/javalib/framework-connectivity.jar:/apex/com.android.tethering/javalib/framework-connectivity-t.jar:/apex/com.android.tethering/javalib/framework-tethering.jar:/apex/com.android.uwb/javalib/framework-uwb.jar:/apex/com.android.virt/javalib/framework-virtualization.jar:/apex/com.android.wifi/javalib/framework-wifi.jar
boot-image = system/framework/boot.art:system/framework/boot-framework-adservices.art

Bug: 286381070
Test: m dist out/dist/boot.zip
Change-Id: I258479ffbdf199091290b074329ff1b43db2e669