feat: add inline-ignore

[kounoike]

add inline-ignore feature.
this resolves #237

[vl-kp]

someone please merge this PR

[rhysd]

This PR is not acceptable because

• no test
• no document
• it cannot ignore errors in the middle of a multi-line string like below

  # How can we ignore the error from the unknown variable `hoge`?
  - run: |
      ...
      ...
      ${{ hoge }}

The feature requested at #237 is more complicated than it looks actually.

[kounoike]

@rhysd Could you merge this PR?

• I wrote test
• I wrote document
• it can ignore error in multi-line string

        # actionlint ignore=potentially untrusted
        run: |
          echo "hello"
          echo '${{ github.event.head_commit.author.name }}'
          echo "hello"

I hope to have a constructive discussion.

[rhysd]

Thank you for addressing some of my comments.

it can ignore error in multi-line string

That's possible because the error position is poor.

I'm sorry that I was not able to describe my concern clearly.

For example,

L10 - run: |
L11    ...
L12    ...
L13    ${{ hoge }}

When an error is found at L13, actionlint reports an error happened at L10. So implementation in this branch somehow currently works fine and the ignore comment can remove the error.

However, when we improve the error position in the future and actionlint can report an error happened at L13, then this implementation will break. The ignore comment above L10 cannot remove an error at L13. And there is no possible fix in that case.

So this implementation happens to work correctly for now, but it's depending on poor error location. Once the poor error location issue is solved, this implementation no longer works.

This is what I concern.