Uniparser

1. show format_exc while error on webui
2. use rule.context by default for parsing
3. add GlobalConfig.init_context for init default context
4. make parse_rule of webui async for fastapi

- fix CONTEXT pollution for webui
- support PURE_UNIPARSER env variable to install without parsers

- fix console error logs
- handle exceptions for InputCallbacks
- add sidebar for toc of rules

fix fix_relative_path
fix some UI issue

- refactor input_callback instead of resp_callback
- no backward compatibility

- refactor resp_callback as CrawlerRule's key

- fix python-const parser