Make EqualModules a free function.

Bug: 377723687
Test: Unit tests and compare the ninja and mk files generated.
Change-Id: I7e00f09a15f2857f58bea70bcedc4798630a40bc
diff --git a/android/apex.go b/android/apex.go
index 4e92f44..39de6de 100644
--- a/android/apex.go
+++ b/android/apex.go
@@ -196,7 +196,7 @@
 		return false
 	}
 
-	if !ctx.EqualModules(ctx.Module(), module) {
+	if !EqualModules(ctx.Module(), module) {
 		if moduleInfo, ok := OtherModuleProvider(ctx, module, DepInSameApexInfoProvider); ok {
 			if !moduleInfo.Checker.OutgoingDepIsInSameApex(depTag) {
 				return false