Option to only create annotations instead of using a separate check run

[Purpzie]

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• Is this related to the actions-rs Actions?
  If you think it's a problem related to Github Actions in general, use GitHub Community forum instead: https://github.community
• You've read the Contributing section about feature requests: https://github.com/actions-rs/.github/blob/master/CONTRIBUTING.md#feature-requests
• Is this something you can debug and fix? Send a pull request! Bug fixes and documentation fixes are welcome.

Motivation

It would be nice if actions-rs/clippy-check worked like actions-rs/cargo, and just created annotations. This would prevent it from creating an unnecessary check run to display the results in a table. The cargo action doesn't display the full details like clippy-check does.

Workflow example

- uses: actions/rs@clippy-check@v1
  with:
    token: ${{ secrets.GITHUB_TOKEN }}
    only-annotations: true

Additional context

This would also be useful to prevent #45 from happening until that gets fixed one day.