Convert the following singletons to use ModuleProxy:

buildTargetSingleton
exportedJavaDeclarationsLibrarySingleton
javaFuzzPackager
kytheExtractAllSingleton
kytheExtractJavaSingleton
kytheExtractRustSingleton
lintSingleton
logtagsSingleton
makeVarsSingleton
ndkAbiDiffSingleton
ndkAbiDumpSingleton
phonySingleton
platformCompatConfigSingleton
sdkSingleton

Bug: 377723687
Test: Unit tests and compare the ninja and mk files generated.
Change-Id: I625ac8a209ca93755b2ba232202cfb44ecefde0a
diff --git a/filesystem/filesystem.go b/filesystem/filesystem.go
index 28eb36d..d4ea6a3 100644
--- a/filesystem/filesystem.go
+++ b/filesystem/filesystem.go
@@ -1525,10 +1525,11 @@
 	})
 }
 
-func (f *filesystem) MakeVars(ctx android.MakeVarsModuleContext) {
+func (f *filesystem) MakeVars(ctx android.MakeVarsModuleContext) []android.ModuleMakeVarsValue {
 	if f.Name() == ctx.Config().SoongDefinedSystemImage() {
-		ctx.StrictRaw("SOONG_DEFINED_SYSTEM_IMAGE_PATH", f.output.String())
+		return []android.ModuleMakeVarsValue{{"SOONG_DEFINED_SYSTEM_IMAGE_PATH", f.output.String()}}
 	}
+	return nil
 }
 
 func setCommonFilesystemInfo(ctx android.ModuleContext, m Filesystem) {