Add support for specifying LOCAL_SDK_LIBRARIES for prebuilts.

This new variable allows specifying libraries like this:
LOCAL_SDK_VERISON := 25
LOCAL_SDK_LIBRARIES := org.apache.http.legacy,
which would automatically pick up the prebuilt OAHL prebuilt
from prebuilts/sdk/25/public/org.apache.http.legacy.jar

Test: In master with uiautomator.
Bug: 77575476
Change-Id: Id8d92176f5b608c2bcea622b6aed4aa27c32e000