Add property Exportable to aconfig_declarations

Only when aconfig_declarations explicitly set this property true,
its flags will be repackaged.

If a java_aconfig_library has mode "exported", its corresponding
aconfig_declarations must have exportable prop set to true.

Test: Added unit tests and CI

Bug: 310504781

Ignore-AOSP-First: this change will be cherry picked to aosp
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:e4527f3010b3fd6f33948a15a9b4fdc944da34f0)
Merged-In: Ie9526e3755a6e7d142b377d5dd85a1bc60ffabc5
Change-Id: Ie9526e3755a6e7d142b377d5dd85a1bc60ffabc5

aconfig/aconfig_declarations.go

@@ -40,6 +40,9 @@ type DeclarationsModule struct {
 
 		// Container(system/vendor/apex) that this module belongs to
 		Container string
+
+		// The flags will only be repackaged if this prop is true.
+		Exportable bool
 	}
 
 	intermediatePath android.WritablePath
@@ -159,6 +162,7 @@ func (module *DeclarationsModule) GenerateAndroidBuildActions(ctx android.Module
 	android.SetProvider(ctx, android.AconfigDeclarationsProviderKey, android.AconfigDeclarationsProviderData{
 		Package:                     module.properties.Package,
 		Container:                   module.properties.Container,
+		Exportable:                  module.properties.Exportable,
 		IntermediateCacheOutputPath: intermediateCacheFilePath,
 		IntermediateDumpOutputPath:  intermediateDumpFilePath,
 	})