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
Merged-In: Iab1437027fcbe4b7876207ec7605a765ba667b52
Change-Id: Iab1437027fcbe4b7876207ec7605a765ba667b52
(cherry picked from commit b1e43a9005)

Android.bp

@@ -26,6 +26,7 @@ cc_library_headers {
             ],
         },
     },
+    min_sdk_version: "29",
 
 }
 
@@ -59,4 +60,5 @@ cc_library_shared {
             exclude_shared_libs: ["libvndksupport"],
         },
     },
+    min_sdk_version: "29",
 }