RFR: 2170: Warn on trailing period in PR titles [v3]

[Zhao Song]

> This patch is trying to add a new jcheck called "issuestitle". This jcheck would check if the issue's title has a trailing period or leading lowercase letter. And we would like to configure "issuestitle" jcheck as warning in the repos since in some cases, trailing periods are valid.
> 
> When implementing this, I found that although we can configure a jcheck as warning in the jcheck configuration file(.jcheck/conf), we fail to differentiate between jchecks as error and jchecks as warning. When jchecks fail as warnings, they cause the local jcheck to exit with a status code of 1. Also, they will be integration blockers when Skara bots evaluate pull requests.  Therefore, in this patch, I also make Skara CLI and Skara bots be able to handle jcheck warnings properly.

Zhao Song has updated the pull request incrementally with one additional commit since the last revision:

  fix test

-------------

Changes:
  - all: https://git.openjdk.org/skara/pull/1638/files
  - new: https://git.openjdk.org/skara/pull/1638/files/2a4e6ee0..584bcbfe

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1638&range=02
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1638&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/skara/pull/1638.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1638/head:pull/1638

PR: https://git.openjdk.org/skara/pull/1638