RFR: 1851: Fold CSR bot into PR bot [v3]

[Zhao Song]

> In this patch, the whole csr bot module is removed. 
> 
> Original CSRPullRequestBot is deleted. The functionality of this bot has been moved to `CheckRun`.
> 
> Original CSRIssueBot has been moved to pr bot module. PullRequestBotFactory would generate a CSRIssueBot for every configured Issue project.

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

 - fix a problem
 - fix a problem
 - renamed some classes
 - improve PullRequestBotFactoryTest

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

Changes:
  - all: https://git.openjdk.org/skara/pull/1492/files
  - new: https://git.openjdk.org/skara/pull/1492/files/d0a0d2f0..f06cf10e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1492&range=02
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1492&range=01-02

  Stats: 26 lines in 7 files changed: 3 ins; 9 del; 14 mod
  Patch: https://git.openjdk.org/skara/pull/1492.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1492/head:pull/1492

PR: https://git.openjdk.org/skara/pull/1492