* add PP-OCRv2

* add PP-OCRv2 benckmark

* update app

* update introduction

* update PP-OCRv2 introduction

* add pipeline of PP-OCRv2

* add PP-OCRv3

* update benckmark

* add paddleocr to requirements

* update

* support paddleocr 2.6.0.1

* rm print code

* add image download

* add model train

* update PP-OCRv3 ref

* update doc

* update doc

* update PP-OCR info

* add PP-StructureV2

* update doc

* merge upstream

* update info.yaml

* test = add the PP-YOLOv2 Demo to ModerCenter

* test = update the PP-YOLOv2 Demo to ModerCenter

* test = update the PP-YOLOv2 Demo to ModerCenter

* test = add the folders for related models
Co-authored-by: NYang <yangyehua@baidu.com>