RFR: 1625: Validate input from /summary command [v5]

[Zhao Song]

> 1.  Added validation to SummaryCommand.
> 2. If exceptions are thrown when the bot is evaluating the current status of the pr, the exceptions will be treated as integration blocker.

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

  fix a whitespace issue

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Changes:
  - all: https://git.openjdk.org/skara/pull/1401/files
  - new: https://git.openjdk.org/skara/pull/1401/files/492838af..b8a01eff

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1401&range=04
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1401&range=03-04

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/skara/pull/1401.diff
  Fetch: git fetch https://git.openjdk.org/skara pull/1401/head:pull/1401

PR: https://git.openjdk.org/skara/pull/1401