Implement dataconnect:execute command.

[yuchenshi]

Description

This adds a new command to execute Data Connect operations.

Scenarios Tested

See Sample Commands below for more.

Sample Commands

firebase dataconnect:execute MyOperation
# REMOVED for now: firebase dataconnect:execute my-connector MyOperation
firebase dataconnect:execute ./my-file.gql
firebase dataconnect:execute ./my-file.gql MyOperation

[yuchenshi]

This doesn't work quite nicely since errors thrown (below, if any) are also logged to stdout (globally handled). Piping to jq for example can choke on the extra output

[yuchenshi]

As discussed internally, I tried to throw an error if options.nonInteractive but that creates a false positive when --json is passed, since --json right now implies options.nonInteractive (handled globally).

I don't think erroring on --json matches user intention, so I left that part out.

[fredzqm]

Can you limit the scope of this PR to a minimum set of API that has no ongoing debates? Probably will make it easier to make progress and unblock the primary seed data CUJ in quick start.

# Yes, please!
firebase dataconnect:execute ./my-file.gql

# Let's defer.
# The tests CreatePlayer example made me nervous. tests appear like the folder name for someone new to FDC.
firebase dataconnect:execute my-connector MyOperation

# Prefer to defer it. Though won't block on it.
# There is less ambiguity between file and operation name, we can detect based on convention.
# Though the alternative `-n MyOperation` is simple, unambitious. It also allows taking multiple files. Multi seed file is a super common use case.
firebase dataconnect:execute MyOperation
firebase dataconnect:execute ./my-file.gql MyOperation

[yuchenshi]

Removed connector and --impersonate. Keeping operation name as a positional argument per offline discussion

[joehan]

/gemini review

[gemini-code-assist]

Code Review

This PR introduces a new firebase dataconnect:execute command, which is a great addition for developers working with Data Connect. The implementation is comprehensive, covering various ways to specify queries and variables, including from files and stdin, which improves usability.

I've left a couple of suggestions to improve error handling in JSON parsing functions. Making error messages more precise will help users debug their inputs more effectively.

Overall, this is a solid contribution that enhances the Data Connect developer experience.

[joehan]

Some small things and a general concern about the deeply nested code. If feasible, it would be great to simplify a bit, but if not, I won't block on it.

[joehan]

Highly tempted to do this with functional programming as .filter(...).map(...).reduce(...), but this probably reads cleaner as is.