feat: add platform to events table

[frank-zsy]

close #1437

[frank-zsy]

As there are lots of changes made in this PR, I will record the changes while making them.

• Add platform column in the database.
• Reimport all the GitHub and Gitee events into events table and delete gh_events table
• Modify the database schema file
• Modify label data structure. Put repo/org/user names from comments to name field to make sure the data exists after parsing to JSON
• Modify github_repo to github.repo and same to orgs and users. So we can easily add other platforms data.
• Modify the label_data_utils to fit the new label structure.
• Modify the query option structure.
• Modify the underlying libs to fit the new query option structure.

[frank-zsy]

I will merge this PR first since all basic functionalities are already ready to use, more detailed changed will be added in the future.