Move modules containing ART, conscrypt and i18n from libcore

This change moves the definitions of the following libraries which
directly include ART, conscrypt and i18n stubs, and their associated
java_system_modules from libcore to build/soong/java/core-libraries.
* core.current.stubs
* core-current-stubs-system-modules
* core.module_lib.stubs
* core-module-lib-stubs-system-modules
* legacy.core.platform.api.stubs
* legacy-core-platform-api-stubs-system-modules
* stable.core.platform.api.stubs
* stable-core-platform-api-stubs-system-modules

Bug: 193311122
Test: m droid
Change-Id: I42c4a0b5322897d40ecf41de088152dbdc526c96