Unifying dataflow & expressions

[philrz]

[philrz]

A nice test for success will be when we can show Zed querying the giant data files described in #4838. This might take the form of first leveraging jq's ability to stream input & create paths, since Zed would need some kind of flag to stream instead of trying to read whole values into memory. Thankfully the jq paths and Zed paths are expected to look the same with JSON input, which should make this possible.

[philrz]

As a team we've discussed whether there should be a syntax for calling functions like methods (|> was one of the proposals). In a recent discussion we agreed we might revisit that topic after we've addressed what's already linked to this Epic.