ARROW-6862: [Developer] Check pull request title

[kou]

It checks pull request title periodically.

If a checked pull request doesn't start with ARROW-XXX, github-actions bot comments how to contribute.

See .github/workflows/pull_request/title_check.md for comment content.

[kou]

Demo: kou#6

[github-actions]

https://issues.apache.org/jira/browse/ARROW-6862

[wesm]

What do you think about permitting PRs with [MINOR] or similar to not have a JIRA? It's not that much of a nuisance to have the bot commenting on minor PRs, though

[wesm]

(very cool by the way)

[kou]

I think that indicating "no JIRA pull request" by title is fragile. We need to add a rule to our how to contribute guideline. We may forget the new rule.

In this change, the check doesn't comment a pull request that already has any comments:
https://github.com/apache/arrow/pull/5628/files#diff-3cbfc93b2e63cf9e17728203104d36a0R53

It means that we can prevent "open an issue on JIRA" comment by just commenting "This is a trivial fix." by ourselves like #5604 (review) .

I think that this is simpler and easy to understand the situation of the pull request.
What do you think about this approach?

[kou]

I think that Travis CI failure is unrelated.

[kou]

No more comments?
I'll merge this tomorrow.

[kou]

I'll merge this.

[wesm]

Thanks @kou (I agree, trivial fixes are rare enough that it is not a big deal)