feat(web_api): pdf parse API and function implementation

[yzztin]

• refactor the code implementation in projects/web_api
• added md_content and content_list result to return in the functions pipe.operators.PipeResult.dump_md and pipe.operators.PipeResult.dump_content_list

#1396

Thanks for your contribution and we appreciate it a lot. The following instructions would make your pull request more healthy and more easily get feedback. If you do not understand some items, don't worry, just make the pull request and seek help from maintainers.

Motivation

1. the projects/web_api seems outdate.
2. I think return the result in the functions such as pipe.operators.PipeResult.dump_md is really important.

Modification

1. added new file for web_api
2. added md_content and content_list result to return in the functions pipe.operators.PipeResult.dump_md and pipe.operators.PipeResult.dump_content_list

BC-breaking (Optional)

Fully compatible.

Use cases (Optional)

See projects/web_api/pdf_parse_main.py.

Checklist

Before PR:

• Pre-commit or other linting tools are used to fix the potential lint issues.
• Bug fixes are fully covered by unit tests, the case that causes the bug should be added in the unit tests.
• The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, like docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with those projects.
• CLA has been signed and all committers have signed the CLA in this PR.

[github-actions]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

[yzztin]

I have read the CLA Document and I hereby sign the CLA

[myhloli]

Thank you for submitting the fix. Here are a few important points that need to be addressed:

1. The master branch of this repository does not accept code submissions; all code should be submitted to the dev branch and will be merged into master during the next release.
2. The file magic_pdf/pipe/operators.py has been moved to magic_pdf/operators/pipes.py in the dev branch, and two methods, get_markdown and get_contentlist, have been added.
3. Please try checking out to the dev branch and adjust the code in your project according to the latest status of the dev branch.

We appreciate your effort once again. Thank you.

[yzztin]

Thank you for submitting the fix. Here are a few important points that need to be addressed:

1. The master branch of this repository does not accept code submissions; all code should be submitted to the dev branch and will be merged into master during the next release.
2. The file magic_pdf/pipe/operators.py has been moved to magic_pdf/operators/pipes.py in the dev branch, and two methods, get_markdown and get_contentlist, have been added.
3. Please try checking out to the dev branch and adjust the code in your project according to the latest status of the dev branch.

We appreciate your effort once again. Thank you.