VectorStore -> BasePydanticVectorStore, also get/delete_nodes, clear() (#13439)

docs/BUILD

docs/docs/examples/low_level/vector_store.ipynb

llama-index-core/llama_index/core/bridge/langchain.py

...ex-core/llama_index/core/indices/document_summary/base.py

...a-index-core/llama_index/core/indices/multi_modal/base.py

...ex-core/llama_index/core/indices/multi_modal/retriever.py

...-index-core/llama_index/core/indices/vector_store/base.py

...index-core/llama_index/core/langchain_helpers/__init__.py

llama-index-core/llama_index/core/llms/loading.py

llama-index-core/llama_index/core/llms/utils.py

...index-core/llama_index/core/node_parser/text/langchain.py

...dex-core/llama_index/core/postprocessor/rankGPT_rerank.py

llama-index-core/llama_index/core/program/utils.py

...core/llama_index/core/prompts/default_prompt_selectors.py

llama-index-core/llama_index/core/storage/storage_context.py

llama-index-core/llama_index/core/vector_stores/simple.py

llama-index-core/llama_index/core/vector_stores/types.py

llama-index-core/pyproject.toml

llama-index-core/tests/output_parsers/test_base.py

llama-index-core/tests/text_splitter/BUILD