partners[milvus]: add dynamic field (#24544)
add dynamic field feature to langchain_milvus
more unittest, more robustic
plan to deprecate the `metadata_field` in the future, because it's
function is the same as `enable_dynamic_field`, but the latter one is a
more advanced concept in milvus
Signed-off-by: ChengZi <chen.zhang@zilliz.com>
Co-authored-by: Erick Friis <erick@langchain.dev>
