Propagate min_sdk_version to apexer

This way it will be correctly set in the auto-generated
AndroidManifest.xml.

Bug: 171096530
Bug: 157078772
Test: m
Change-Id: I268f08ca5dd17fa9d6763ad70cc9a3f83891a8d6
Merged-In: I268f08ca5dd17fa9d6763ad70cc9a3f83891a8d6
(cherry picked from commit 97fd4923)