Use Source_apex_name for LOCAL_MODULE in Soong gen Android.mk

For versioned mainline prebuilts, the version is getting written to
`LOCAL_MODULE` property in the generated Android.mk file, even when they
set Source_apex_name. This CL uses Source_apex_name as the LOCAL_MODULE
so that the versioned prebuilt does not get elided from product
packaging.

Test: m nothing --no-skip-soong-tests
Bug: 405153030
Change-Id: I15a6c6d8a3906cced87771ddde05563209c26bc2
diff --git a/android/androidmk.go b/android/androidmk.go
index 694f5d6..5adc849 100644
--- a/android/androidmk.go
+++ b/android/androidmk.go
@@ -510,6 +510,9 @@
 	a.EntryMap = make(map[string][]string)
 	base := mod.base()
 	name := base.BaseModuleName()
+	if bmn, ok := mod.(baseModuleName); ok {
+		name = bmn.BaseModuleName()
+	}
 	if a.OverrideName != "" {
 		name = a.OverrideName
 	}