Add support for autocompleting/manipulating --query argument

[jamesls]

Not sure exactly what this would look like, but I want to:

a) Attempt to autocomplete the JMESPath expression for --query. This seems tough. b) Live update in a vsplit/hsplit pane the result of applying the query expression provided so far against sample generated output.

I demo'd a POC of this with vim + jpterm at re:Invent, would like to have a similar feature as well.

[donnemartin]

Something like this might be cool, from ptpython: