Provide extended allocators interface (e.g. grow/realloc) like Boost.Container

[Boost.Container allocators support extra interfaces than the standard allocator requirements](https://www.boost.org/doc/libs/1_73_0/doc/html/container/extended_allocators.html).

Some of these functions are useful even to C libraries that used to enjoy `realloc()` like features. So this extra interface is useful even if we're not planning to use it with standard containers.

It'd be nice if Boost.Interprocess could provide a few of these features for its [allocators](https://www.boost.org/doc/libs/1_73_0/doc/html/interprocess/allocators_containers.html) as [`managed_shared_memory`](https://www.boost.org/doc/libs/1_73_0/doc/html/interprocess/managed_memory_segments.html#interprocess.managed_memory_segments.managed_memory_segment_features.allocate_deallocate) has plenty of features not found in Boost.Container allocators and we cannot use Boost.Container extended allocators to manage preallocated memory regions.

まず、リンクされている Boost.Container の拡張 allocator のドキュメントを読み、次に Boost.Interprocess の allocator と managed_shared_memory のドキュメントと比較します。あらかじめ確保されたメモリ領域でサポートできる allocator 操作を特定し、必要なインターフェースとテストを定義します。Boost.Interprocess の allocator を通じて、標準コンテナの要件に依存せずに選択した拡張操作を利用できるようになれば完了です。

索引モデルが issue の本文から書いたものです。