Add aconfig flag support for android_app

This change adds an overrideable property flags_packages to android_app,
which is used to list the aconfig_declarations module names that the app
depends on. The build action of android_app is modified to pass all
flags text file provided by the aconfig_declarations to aapt2 link as
--feature-flags arguments.

Test: m nothing --no-skip-soong-tests
Bug: 306024510
Change-Id: I4924f88b9954950cc1936a472cd7ac70f41add5d

java/aar.go

@@ -349,6 +349,7 @@ type aaptBuildActionOptions struct {
 	excludedLibs                   []string
 	enforceDefaultTargetSdkVersion bool
 	extraLinkFlags                 []string
+	aconfigTextFiles               android.Paths
 }
 
 func (a *aapt) buildActions(ctx android.ModuleContext, opts aaptBuildActionOptions) {
@@ -529,7 +530,8 @@ func (a *aapt) buildActions(ctx android.ModuleContext, opts aaptBuildActionOptio
 		transitiveAssets = android.ReverseSliceInPlace(staticDeps.assets())
 	}
 	aapt2Link(ctx, packageRes, srcJar, proguardOptionsFile, rTxt,
-		linkFlags, linkDeps, compiledRes, compiledOverlay, transitiveAssets, splitPackages)
+		linkFlags, linkDeps, compiledRes, compiledOverlay, transitiveAssets, splitPackages,
+		opts.aconfigTextFiles)
 	// Extract assets from the resource package output so that they can be used later in aapt2link
 	// for modules that depend on this one.
 	if android.PrefixInList(linkFlags, "-A ") {
@@ -1193,7 +1195,7 @@ func (a *AARImport) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 
 	transitiveAssets := android.ReverseSliceInPlace(staticDeps.assets())
 	aapt2Link(ctx, a.exportPackage, nil, proguardOptionsFile, a.rTxt,
-		linkFlags, linkDeps, nil, overlayRes, transitiveAssets, nil)
+		linkFlags, linkDeps, nil, overlayRes, transitiveAssets, nil, nil)
 
 	a.rJar = android.PathForModuleOut(ctx, "busybox/R.jar")
 	resourceProcessorBusyBoxGenerateBinaryR(ctx, a.rTxt, a.manifest, a.rJar, nil, true)