Lifecycle of `ChatEditingModifiedDocumentEntry` and `ChatEditingModifiedNotebookEntry`

[bpasero]

Found an error telemetry report about many undisposed of these:

vscode/src/vs/workbench/contrib/chat/browser/chatEditing/chatEditingSession.ts

Lines 1062 to 1069 in a69f194

	const doCreate = async (chatKind: ChatEditKind) => {
	if (this._notebookService.hasSupportedNotebooks(notebookUri)) {
	return await ChatEditingModifiedNotebookEntry.create(notebookUri, multiDiffEntryDelegate, telemetryInfo, chatKind, initialContent, this._instantiationService);
	} else {
	const ref = await this._textModelService.createModelReference(resource);
	return this._instantiationService.createInstance(ChatEditingModifiedDocumentEntry, ref, multiDiffEntryDelegate, telemetryInfo, chatKind, initialContent);
	}
	};

At a quick glance it was not obvious to me that we ever dispose of these 2?