Update min_sdk_version from SdkSpec to ApiLevel

This relands aosp/2457063. The original change broke T and U since those
branches still contain soong modules of type (kind+level). Those soong
modules have been cleaned up now

Test: Used go/abtd to test T and U branches with this change

Bug: 208456999
Change-Id: I0ef7933c055f88cb512a02108f1173e51156ef1c
diff --git a/java/hiddenapi_modular.go b/java/hiddenapi_modular.go
index e2db0cd..c6176e6 100644
--- a/java/hiddenapi_modular.go
+++ b/java/hiddenapi_modular.go
@@ -1278,7 +1278,7 @@
 	uncompressDex bool
 
 	// The minimum sdk version that the dex jar will be used on.
-	minSdkVersion android.SdkSpec
+	minSdkVersion android.ApiLevel
 }
 
 // bootDexInfoByModule is a map from module name (as returned by module.Name()) to the boot dex