* Adding splitting function
* Adding test for split by function
* Adding release note for feat adding split by function
* Fixing release note for split_by_function
* Fixing issue with splitting_function non callable
* nit: fixing value error in documentsplitter for split_by
* Add custom serde
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Co-authored-by: Giovanni Alzetta <giovannialzetta@gmail.com>
Co-authored-by: Vladimir Blagojevic <dovlex@gmail.com>