RFR: 1553: Update PR titles automatically from JBS

[Zhao Song]

As Magnus and Erik proposed, Skara bot should rewrite PR titles to a canonical form(numbers for the bugId, followed by a ':' and then the bug title, e.g. "1: This is an issue").
Especially, Skara bot should rewrite PR title in the form of "JDK-1 This is an issue" or "JDK-1: This is an issue" to the canonical form.

Furthermore, sometimes, a user would update the issue title in JBS and forget updating the pr title. With this patch, If the change is minor like changing the case of some characters or adding/removing spaces, Skara bot will update it automatically for the user, otherwise, Skara bot would still add an integration blocker " ⚠️ Title mismatch between PR and JBS.",

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Commit messages:
 - SKARA-1553

Changes: https://git.openjdk.org/skara/pull/1631/files
  Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1631&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-1553
  Stats: 51 lines in 4 files changed: 41 ins; 3 del; 7 mod
  Patch: https://git.openjdk.org/skara/pull/1631.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1631/head:pull/1631

PR: https://git.openjdk.org/skara/pull/1631