Export RunBp2BuildTestCaseSimple() in testing.go

This is to support the migration of conversion tests to be next
to the files they're testing

Bug: 242070498
Test: m bp2build
Change-Id: I66243d420743273e7ebad70886cfe690740182c4
diff --git a/bp2build/testing.go b/bp2build/testing.go
index b64678d..a0d512f 100644
--- a/bp2build/testing.go
+++ b/bp2build/testing.go
@@ -71,7 +71,7 @@
 	return false
 }
 
-func runBp2BuildTestCaseSimple(t *testing.T, tc Bp2buildTestCase) {
+func RunBp2BuildTestCaseSimple(t *testing.T, tc Bp2buildTestCase) {
 	t.Helper()
 	RunBp2BuildTestCase(t, func(ctx android.RegistrationContext) {}, tc)
 }