* add type annotations to run,warm_up, __str__
* none and any type annotations
* type annotations
* __init__ return type annotation
* list[Document] instead of Any return type annotations
* fmt
* typing
* add run_async return type annotation for LinkContentFetcher
* run_async return type annotations
* fixing docstrings
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Co-authored-by: David S. Batista <dsbatista@gmail.com>