Create soong-generated filesystem diff test

Running `m soong_generated_filesystem_tests` will diff the
soong-generated system image with the make-generated one.

Currently, this test fails, but we can start working on narrowing it
down now.

Bug: 371351099
Test: m soong_generated_filesystem_tests
Change-Id: I364677f09286652e4577bf9e0d16481998dfd258
diff --git a/filesystem/filesystem.go b/filesystem/filesystem.go
index a26fac7..14501bb 100644
--- a/filesystem/filesystem.go
+++ b/filesystem/filesystem.go
@@ -35,7 +35,7 @@
 }
 
 func registerBuildComponents(ctx android.RegistrationContext) {
-	ctx.RegisterModuleType("android_filesystem", filesystemFactory)
+	ctx.RegisterModuleType("android_filesystem", FilesystemFactory)
 	ctx.RegisterModuleType("android_filesystem_defaults", filesystemDefaultsFactory)
 	ctx.RegisterModuleType("android_system_image", SystemImageFactory)
 	ctx.RegisterModuleType("avb_add_hash_footer", avbAddHashFooterFactory)
@@ -144,7 +144,7 @@
 // modules in the filesystem image are built for the target device (i.e. Android, not Linux host).
 // The modules are placed in the filesystem image just like they are installed to the ordinary
 // partitions like system.img. For example, cc_library modules are placed under ./lib[64] directory.
-func filesystemFactory() android.Module {
+func FilesystemFactory() android.Module {
 	module := &filesystem{}
 	module.filterPackagingSpec = module.filterInstallablePackagingSpec
 	initFilesystemModule(module, module)
@@ -177,6 +177,13 @@
 	unknown
 )
 
+type FilesystemInfo struct {
+	// A text file containing the list of paths installed on the partition.
+	FileListFile android.Path
+}
+
+var FilesystemProvider = blueprint.NewProvider[FilesystemInfo]()
+
 func (f *filesystem) fsType(ctx android.ModuleContext) fsType {
 	typeStr := proptools.StringDefault(f.properties.Type, "ext4")
 	switch typeStr {
@@ -227,6 +234,10 @@
 
 	f.fileListFile = android.PathForModuleOut(ctx, "fileList").OutputPath
 	android.WriteFileRule(ctx, f.fileListFile, f.installedFilesList())
+
+	android.SetProvider(ctx, FilesystemProvider, FilesystemInfo{
+		FileListFile: f.fileListFile,
+	})
 }
 
 func (f *filesystem) appendToEntry(ctx android.ModuleContext, installedFile android.OutputPath) {