Set min_sdk_version to be part of mainline modules

Modules contributing mainline modules (APK/APEX) should set
min_sdk_version as well as apex_available.

For now setting min_sdk_version doesn't change build outputs.
But build-time checks will be added soon.

Bug: 152655956
Test: m
Change-Id: I2b4e41a40f4bc938cccacc116ad3779b6ff31eab

packages/CtsShim/build/Android.bp

@@ -79,6 +79,7 @@ android_app {
         "com.android.apex.cts.shim.v2_unsigned_payload",
         "com.android.apex.cts.shim.v3",
     ],
+    min_sdk_version: "24",
 }
 
 //##########################################################
@@ -152,4 +153,5 @@ android_app {
         "com.android.apex.cts.shim.v2_unsigned_payload",
         "com.android.apex.cts.shim.v3",
     ],
+    min_sdk_version: "24",
 }