cmd/run: task field cleanup

[buchanae]

I've been using this command a lot lately, and noticed a few areas that need cleaning up:

• tags, environ, and resources can be printed as empty dictionaries
• everything is namespaced under /opt/funnel/ which seems unnecessary
• stdout and stderr are always included, which is a legacy hack for stdout/err log streaming, I think
• task name has escaped double quotes. single quotes look nicer in the terminal/JSON
• task name is prefixed with "Funnel run: " which adds no value.

Before

./build/bin/funnel-darwin-amd64 run --print 'echo $I > $O' -i I=swift://buchanan/foo.txt -o O=swift://buchanan/out.txt
{
  "name": "Funnel run: sh -c \"echo $I \u003e $O\"",
  "inputs": [
    {
      "name": "I",
      "url": "swift://buchanan/foo.txt",
      "path": "/opt/funnel/inputs/buchanan/foo.txt"
    }
  ],
  "outputs": [
    {
      "name": "O",
      "url": "swift://buchanan/out.txt",
      "path": "/opt/funnel/outputs/buchanan/out.txt"
    }
  ],
  "resources": {

  },
  "executors": [
    {
      "image": "alpine",
      "command": [
        "sh",
        "-c",
        "echo $I \u003e $O"
      ],
      "workdir": "/opt/funnel",
      "stdout": "/opt/funnel/outputs/stdout-0",
      "stderr": "/opt/funnel/outputs/stderr-0",
      "env": {
        "I": "/opt/funnel/inputs/buchanan/foo.txt",
        "O": "/opt/funnel/outputs/buchanan/out.txt"
      }
    }
  ],
  "tags": {
  }
}

After

RJHB552 funnel (funnel-run-cleanup-2)
funnel run --print 'echo $I > $O' -i I=swift://buchanan/foo.txt -o O=swift://buchanan/out.txt
{
  "name": "sh -c 'echo $I \u003e $O'",
  "inputs": [
    {
      "name": "I",
      "url": "swift://buchanan/foo.txt",
      "path": "/inputs/buchanan/foo.txt"
    }
  ],
  "outputs": [
    {
      "name": "O",
      "url": "swift://buchanan/out.txt",
      "path": "/outputs/buchanan/out.txt"
    }
  ],
  "executors": [
    {
      "image": "alpine",
      "command": [
        "sh",
        "-c",
        "echo $I \u003e $O"
      ],
      "env": {
        "I": "/inputs/buchanan/foo.txt",
        "O": "/outputs/buchanan/out.txt"
      }
    }
  ]
}

[buchanae]

Strangely, many of the tests had commands like --sh "sh -c 'exit 1'". Not sure what I removed from funnel run that was allowing that to work :( I removed those commands from the tests.

[buchanae]

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