GitLab

* feat: rename the file generated by command line tools

* feat: add pdf filename as prefix to {span,layout,model}.pdf

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Co-authored-by: icecraft <tmortred@gmail.com>
Co-authored-by: icecraft <xurui1@pjlab.org.cn>

* feat: remove dummpy code, magic_pdf/cli, magic_pdf/train_utils

* feat: expose version in command line

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Co-authored-by: shenguanlin <shenguanlin@pjlab.org.cn>

* feat: refractor cli command

* feat: add docs to describe the output files of cli

* feat: resove review comments

* feat: updat docs about middle.json

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Co-authored-by: shenguanlin <shenguanlin@pjlab.org.cn>