RFR: 1071: auto-set `/csr` flag from JBS state [v4]

[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 one additional commit since the last revision:

  Avoid the bot adding the CSR label again.

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

Changes:
  - all: https://git.openjdk.java.net/skara/pull/1245/files
  - new: https://git.openjdk.java.net/skara/pull/1245/files/a725ac5f..37573bdd

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=skara&pr=1245&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=skara&pr=1245&range=02-03

  Stats: 7 lines in 1 file changed: 6 ins; 0 del; 1 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