feat: add MetadataFilter for SimpleVectorStore and Milvus (#1030)

.changeset/famous-poets-hammer.md

apps/docs/docs/modules/query_engines/metadata_filtering.md

examples/chromadb/preFilters.ts

examples/metadata-filter/milvus.ts

examples/metadata-filter/simple.ts

examples/qdrantdb/preFilters.ts

...s/llamaindex/src/storage/vectorStore/MilvusVectorStore.ts

packages/llamaindex/src/storage/vectorStore/PGVectorStore.ts

...llamaindex/src/storage/vectorStore/PineconeVectorStore.ts

...s/llamaindex/src/storage/vectorStore/SimpleVectorStore.ts

packages/llamaindex/src/storage/vectorStore/types.ts

packages/llamaindex/src/storage/vectorStore/utils.ts

packages/llamaindex/tests/mocks/TestableMilvusVectorStore.ts

...s/llamaindex/tests/vectorStores/MilvusVectorStore.test.ts

...s/llamaindex/tests/vectorStores/SimpleVectorStore.test.ts