RFR: 2198: Backport PRs should check if a CSR is required [v7]

[Zhao Song]

> This patch is trying to let the pr bot automatically requires csr for a backport PR if one of the associated has a resolved CSR.

Zhao Song has updated the pull request incrementally with two additional commits since the last revision:

 - Update bots/pr/src/main/java/org/openjdk/skara/bots/pr/CheckRun.java
   
   Co-authored-by: Erik Joelsson <37597443+erikj79 at users.noreply.github.com>
 - Update bots/pr/src/main/java/org/openjdk/skara/bots/pr/CheckRun.java
   
   Co-authored-by: Erik Joelsson <37597443+erikj79 at users.noreply.github.com>

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Changes:
  - all: https://git.openjdk.org/skara/pull/1623/files
  - new: https://git.openjdk.org/skara/pull/1623/files/c7c6ba58..d4b768dc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1623&range=06
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1623&range=05-06

  Stats: 4 lines in 1 file changed: 0 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/skara/pull/1623.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1623/head:pull/1623

PR: https://git.openjdk.org/skara/pull/1623