RFR: 1071: auto-set `/csr` flag from JBS state [v2]

[Guoxiong Li]

> Hi all,
> 
> Currently, the author of the PR or a reviewer could type `/csr` in the comment to direct the need of the CSR.
> It is good for the bot to automatically scan the `scr for` link and set the `csr` label for the PR.
> 
> This patch adds the automatically scanning feature. And the corresponding tests are added.
> 
> Thanks for taking the time to review.
> 
> Best Regards,
> -- Guoxiong

Guoxiong Li has updated the pull request incrementally with three additional commits since the last revision:

 - Revise the logic of the command '/csr unneeded'
 - Fix the tests.
 - Revise logging.

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

Changes:
  - all: https://git.openjdk.java.net/skara/pull/1245/files
  - new: https://git.openjdk.java.net/skara/pull/1245/files/e8a43a4e..d36ec3a5

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=skara&pr=1245&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=skara&pr=1245&range=00-01

  Stats: 159 lines in 6 files changed: 59 ins; 89 del; 11 mod
  Patch: https://git.openjdk.java.net/skara/pull/1245.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1245/head:pull/1245

PR: https://git.openjdk.java.net/skara/pull/1245