Create Dataset with metadata

Steps:
- [x] pseudo crawl ~10% of C4 web page from Common Crawl @tianjianjiang
- [x] import pseudo crawled dataset on JZ @SaulLu
- [x] run 1st step of extraction:
1. Extract text, HTML head sections, HTML footer sections, HTML Titles section and HTML metadata @SaulLu
2. Change format of URL @SaulLu
3. Extract Timestamp @cccntu @SaulLu
4. Extract Generation Length Sentence @chkla @SaulLu
5. Extract Generation Length Text @chkla @SaulLu
6. Extract Data source @chkla @SaulLu
- [x] run 2nd step of extraction:
1. Extract Website descriptions @shanyas10 @SaulLu
- [x] run 3rd step of extraction:
1. Extract Entities @manandey @SaulLu
2. (option) Extract Entities descriptions @manandey @SaulLu
- [x] run 4th step of extraction:
1. Extract Paragraph @tianjianjiang @SaulLu
* #114
* #125
* annotator (preprocessor) of the metadata
2. Modify entities metadata with paragraph information @manandey @SaulLu
3. Modify generation length with paragraph information @chkla @SaulLu
- [ ] (optional) clean final dataset:
1. Remove empty lines @SaulLu
2. Remove "errors" columns @SaulLu
3. (optional) Gather all metadata into same column @cccntu @timoschick @SaulLu
- [ ] push dataset to Hub @SaulLu

No files or tests are named. Start by reviewing the completed extraction steps and the current dataset output, then work through the remaining checklist items: clean empty lines and error columns as appropriate, gather metadata if required, and push the finished dataset to the Hub.

Written by the indexing model from the issue text.