[Model] Add PP-FormulaNet Model Support (#45626)
* init
* add tests and model_doc
* fix style
* fix
* fix release date
* Restructure to a VLM
* Restructure to a encoder-decoder VLM
* fix style
* update
* fix
* update date
* update
* nit
* last fix repo stuff
* fixup w some last comments
* remove vlm specifics
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Co-authored-by: vasqu <antonprogamer@gmail.com>
