`--output-format json` to `stdout` should not print info logs in json to`stderr` when output stream redirected

[jpadams]

Currently if you redirect stdout via > outfiile or | jq or similar, you get all of the info(?) logs in json format from stderr dumped to the screen. Perhaps this is by design, but I was surprised by that given that I only wanted the output to pipe cleanly to jq. To declutter my screen I used standard redirect of stderr to /dev/null: 2>/dev/null.

Example:
From https://docs.dagger.io/1226/handling-outputs#piping-a-result or https://docs.dagger.io/1228/handling-outputs#piping-a-result (slug update in progress):

This behavior might be called out here in the doc itself:

start local registry on 5042:

docker run -d -p 5042:5000 --restart=always --name localregistry registry:2 

package main

import (
    "dagger.io/dagger"
    "universe.dagger.io/docker"
)

dagger.#Plan & {
    actions: {
        pull: docker.#Pull & {
            source: "alpine"
        }
        push: docker.#Push & {
            image: pull.output
            dest:  "localhost:5042/alpine"
        }
    }
}

looks great with --output-format json:
dagger do push

looks great without redirect:
dagger --output-format json do push

redirects bring out the logs:
dagger --output-format json do push > /tmp/sldjflsdj

dagger --output-format json do push | jq '.result'

related to #2474

[jpadams]

I realize that when redirecting, we might want to give option to redirect logs in json as well, so use stderr for that...

I see this is a compromise. Instead of an explicit flag to turn the logs on, we use separate channel ofstderr. This delivers a noisy experience for a CLI dagger user, but perhaps not enough to change it at this point.