Support container updates

First off: this issue is different than creating LDPC on route to creating an LDP-RS as a member of an LDPC that doesn't exist yet. That particular case was covered in https://github.com/solid/node-solid-server/pull/513.

This issue is about creating or updating an LDPC (ie an LDP-BC, at the time of this writing). It will conform to LDP provided that the information in the update payload doesn't get in the way of changing the containment triples ( https://www.w3.org/TR/ldp/#h-ldpc-put-mbrprops ). So, for example, adding a label to a container (<> rdfs:label "Foo") would be fine, but PUT/PATCH that inserts or deletes ldp:contains relations should not succeed.

The use cases are generally about including additional "metadata" as part of the container description. It is partly discussed in https://github.com/solid/node-solid-server/issues/547 .

If this feature is implemented, https://github.com/solid/node-solid-server/issues/547 can be revisited, and as far as I can tell, the feature where updating a container's description through /.meta can be removed altogether (as interacting directly with the URI in question would be generally preferable.)

Edit: rel="describedBy" .meta in HTTP header can also be dropped as the interaction will only go through container URI, and that .meta will only be internal to the server.

まず、LDP コンテナの更新要件と issue #547 の関連する議論を確認し、次に LDPC URI への更新を処理するサーバーのエントリポイントを特定します。PUT と PATCH のペイロードが、他のメタデータと比較して ldp:contains トリプルをどのように扱うかを確認します。コンテナ URI を通じてコンテナメタデータを更新でき、containment の変更を許可せず、説明されている .meta の動作が不要になれば完了です。