Expand upon Watson NLU for language processing

[jeffpaul]

Is your enhancement related to a problem? Please describe.
Our current integration for Language Processing with Watson NLU is on a per-Post basis and upon Save (plus the WP CLI batch command). It would be great for folks to be able to use the All Posts and All Pages table list views to filter to specific Posts and Pages and then use the Bulk Actions to send those Posts and Pages to NLU for classifying.

Describe the solution you'd like

• UI for filtering in the All Posts and All Pages table list views and then batch sending content for NLU classifying

Designs
n/a

Describe alternatives you've considered
none

Additional context
n/a

[jeffpaul]

Note that #129 is effectively an umbrella issue for this, just with slightly less details for this specific use case (note that 129 covers several other use cases).

[jeffpaul]

This is done, as there's a "Classify" option in the All Posts Bulk Edit dropdown.