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/rro.go b/java/rro.go
index 9d0667c..49737b9 100644
--- a/java/rro.go
+++ b/java/rro.go
@@ -175,11 +175,11 @@
 	return ""
 }
 
-func (r *RuntimeResourceOverlay) MinSdkVersion(ctx android.EarlyModuleContext) android.SdkSpec {
+func (r *RuntimeResourceOverlay) MinSdkVersion(ctx android.EarlyModuleContext) android.ApiLevel {
 	if r.properties.Min_sdk_version != nil {
-		return android.SdkSpecFrom(ctx, *r.properties.Min_sdk_version)
+		return android.ApiLevelFrom(ctx, *r.properties.Min_sdk_version)
 	}
-	return r.SdkVersion(ctx)
+	return r.SdkVersion(ctx).ApiLevel
 }
 
 func (r *RuntimeResourceOverlay) ReplaceMaxSdkVersionPlaceholder(ctx android.EarlyModuleContext) android.SdkSpec {