Introduce module type aconfig_declarations_group

In order to easily manage aconfig_declarations modules and their
corresponding codegen modules, this change introduces a new module type
`aconfig_declarations_group`. The module enables listing codegen modules
by language, and correctly depend on the desired output files using
appropriate tags.

e.g. for an aconfig_declarations_group module "some_group", the rdeps of
the module can:
- gather all intermediates cache files of the aconfig_declarations with
  ":some_group" tag.
- gather generated srcjar files of the listed java_aconfig_library
  modules with ":some_group{.srcjars}" tag.

Output tag support for cc modules and rust modules will be added in
future changes.

Test: m nothing --no-skip-soong-tests
Bug: 320492079
Change-Id: I93d737577f8d00198ed91048dd6e81ef238193cb

aconfig/init.go

@@ -20,6 +20,20 @@ import (
 	"github.com/google/blueprint"
 )
 
+type CodegenInfo struct {
+	// AconfigDeclarations is the name of the aconfig_declarations modules that
+	// the codegen module is associated with
+	AconfigDeclarations []string
+
+	// Paths to the cache files of the associated aconfig_declaration modules
+	IntermediateCacheOutputPaths android.Paths
+
+	// Paths to the srcjar files generated from the java_aconfig_library modules
+	Srcjars android.Paths
+}
+
+var CodegenInfoProvider = blueprint.NewProvider[CodegenInfo]()
+
 var (
 	pctx = android.NewPackageContext("android/soong/aconfig")