ability to post GitHub output only on failures

[LironEr]

It would also be great to have a way to report the output differently in case of "failures".
For example, the report as PR comment can be very noisy in a monorepo with multiple projects reporting as PR comments, but if we can set the PR comment to be only in case of "failure", that would already be a lot less noisy.

Originally posted by @tleunen in #115 (comment)

[LironEr]

Each output will accept

"always" / "on-failure" / "off"

default:

"reportOutput": [
  [
    "github",
    {
      "checkRun": "off",
      "commitStatus": "always",
      "prComment": "always"
    }
  ]
]

@tleunen what do you think?

[tleunen]

Exactly what I had in mind, and you kept true/false in your PR to be backward compatible so this is great.
Thank you!

[LironEr]

Feature available in bundlemon@2.0.0-rc.1