Add RELEASE_ACONFIG_EXTRA_RELEASE_CONFIGS

This build flag causes us to create aconfig flag artifacts for the
given extra release configs.

Bug: 298444886
Test: manual
Change-Id: I10148f6e7318b0477438ed1d8baafbf4dc594c90
diff --git a/android/aconfig_providers.go b/android/aconfig_providers.go
index ee9891d..a47e80f 100644
--- a/android/aconfig_providers.go
+++ b/android/aconfig_providers.go
@@ -43,6 +43,10 @@
 
 var AconfigDeclarationsProviderKey = blueprint.NewProvider[AconfigDeclarationsProviderData]()
 
+type AconfigReleaseDeclarationsProviderData map[string]AconfigDeclarationsProviderData
+
+var AconfigReleaseDeclarationsProviderKey = blueprint.NewProvider[AconfigReleaseDeclarationsProviderData]()
+
 type ModeInfo struct {
 	Container string
 	Mode      string
@@ -112,6 +116,8 @@
 		if dep, ok := OtherModuleProvider(ctx, module, AconfigDeclarationsProviderKey); ok {
 			mergedAconfigFiles[dep.Container] = append(mergedAconfigFiles[dep.Container], dep.IntermediateCacheOutputPath)
 		}
+		// If we were generating on-device artifacts for other release configs, we would need to add code here to propagate
+		// those artifacts as well.  See also b/298444886.
 		if dep, ok := OtherModuleProvider(ctx, module, AconfigPropagatingProviderKey); ok {
 			for container, v := range dep.AconfigFiles {
 				mergedAconfigFiles[container] = append(mergedAconfigFiles[container], v...)