Add support for Waives Redaction functionality

[alastairs]

Is your feature request related to a problem? Please describe. I would like to be able to redact or bookmark documents from my .NET application. The Waives API supports these functions, but I must write custom code to integrate with those APIs directly.

Similarly to other document operations like classification and extraction, I would like a clear and simple API for redacting, highlighting or bookmarking a document.

Additional context The Waives API currently supports redacting and bookmarking, but not highlighting.

[alastairs]

I'd suggest a simple "redact" method that takes an extractor and returns a document with those fields redacted and as bookmarks. _{View in Slack}