add file-annotations option

[2bndy5]

Add an option to enable/disable the use of file annotations. This includes changes to the README, so there might be a conflict with #57.

[2bndy5]

I tested this option on the test repo. In a matrix that runs the action for all versions of clang-tools, only annotations (& thread comments) were enabled for v12. It worked as expected.

[shenxianpeng]

Do you think we need to update the YAML example in README to help users avoid adding duplicate annotaions?

[2bndy5]

Well, following the discussion in #58, it seems that there are several ways to trigger duplicate annotations.
I think I'd propose the example snippets demonstrate using specific event types rather than using this new option.

on:
  pull_request:
    types: [opened, reopened]  # let PR-synchronize events be handled by push events
  push:

The current examples use paths-ignore which is very specific to this repo:

on:
  push:
    paths-ignore: "docs/**"
  pull_request:
    paths-ignore: "docs/**"

[shenxianpeng]

I like your propose 👍

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

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0.0% Duplication

[2bndy5]

I accidentally rebased on an older commit in master, so the commits in #57 now show in this branch's history. Please squash and merge this when ready.

[shenxianpeng]

OK. do you know why the PR action is queued https://github.com/shenxianpeng/test-cpp-linter-action/actions/runs/2236867491
is it related to the change below?

on:
  pull_request:
    types: [opened, reopened]  # let PR-synchronize events be handled by push events
  push:

[2bndy5]

I have no idea. I tried canceling the run (hoping to manually re-start it), but I got a error message from github saying "Failed to cancel workflow." It doesn't seem to be related.

Sometimes, I see a runner in queue when waiting for a github hosted VM to become available, but it doesn't even say that much. 🤷🏼‍♂️

[2bndy5]

It looks like a github problem. I see you closed and re-opened the PR which seemed to have expected results.

[shenxianpeng]

OK, I'm going to squash and merge.