Move dexpreopt.Script to android.RuleBuilder

Move dexpreopt.Script to android.RuleBuilder so that the builder
style can be used in more places.  Also add tests for it.

Test: rule_builder_test.go
Change-Id: I92a963bd112bf033b08899e930094b908acfcdfd
diff --git a/dexpreopt/dexpreopt_test.go b/dexpreopt/dexpreopt_test.go
index 073d463..6e520f1 100644
--- a/dexpreopt/dexpreopt_test.go
+++ b/dexpreopt/dexpreopt_test.go
@@ -15,6 +15,7 @@
 package dexpreopt
 
 import (
+	"android/soong/android"
 	"reflect"
 	"strings"
 	"testing"
@@ -100,7 +101,7 @@
 		t.Error(err)
 	}
 
-	wantInstalls := []Install{
+	wantInstalls := []android.RuleBuilderInstall{
 		{"out/test/oat/arm/package.odex", "/system/app/test/oat/arm/test.odex"},
 		{"out/test/oat/arm/package.vdex", "/system/app/test/oat/arm/test.vdex"},
 	}
@@ -126,7 +127,7 @@
 		t.Error(err)
 	}
 
-	wantInstalls := []Install{
+	wantInstalls := []android.RuleBuilderInstall{
 		{"out/test/oat/arm/package.odex", "/system_other/app/test/oat/arm/test.odex"},
 		{"out/test/oat/arm/package.vdex", "/system_other/app/test/oat/arm/test.vdex"},
 	}
@@ -150,7 +151,7 @@
 		t.Error(err)
 	}
 
-	wantInstalls := []Install{
+	wantInstalls := []android.RuleBuilderInstall{
 		{"out/test/profile.prof", "/system/app/test/test.apk.prof"},
 		{"out/test/oat/arm/package.art", "/system/app/test/oat/arm/test.art"},
 		{"out/test/oat/arm/package.odex", "/system/app/test/oat/arm/test.odex"},