add storage classes

.devcontainer/devcontainer.json

packages/core/package.json

packages/core/src/Document.ts

packages/core/src/Node.ts

packages/core/src/storage/FileSystem.ts

packages/core/src/storage/StorageContext.ts

packages/core/src/storage/constants.ts

packages/core/src/storage/docStore/KeyValDocumentStore.ts

packages/core/src/storage/docStore/SimpleDocumentStore.ts

packages/core/src/storage/docStore/types.ts

packages/core/src/storage/docStore/utils.ts

packages/core/src/storage/graphStore/SimpleGraphStore.ts

packages/core/src/storage/graphStore/types.ts

packages/core/src/storage/indexStore/SimpleIndexStore.ts

packages/core/src/storage/kvStore/SimpleKVStore.ts

packages/core/src/storage/kvStore/types.ts

packages/core/tsconfig.json

pnpm-lock.yaml