RFR: 1357: Add Oracle copyright header format check to jcheck [v2]

[Zhao Song]

> This patch introduces a copyright jcheck.
> For pull requests, the check checks the copyright header in all modified files(if the file name matches the regex in .jcheck/conf)

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

 - add copyright header
 - version 2
 - update
 - review comment

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Changes:
  - all: https://git.openjdk.org/skara/pull/1702/files
  - new: https://git.openjdk.org/skara/pull/1702/files/a0e2dd9b..33bd7217

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1702&range=01
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1702&range=00-01

  Stats: 778 lines in 17 files changed: 409 ins; 342 del; 27 mod
  Patch: https://git.openjdk.org/skara/pull/1702.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1702/head:pull/1702

PR: https://git.openjdk.org/skara/pull/1702