RFR: SKARA-1096: New command and label for JEPs, similar to CSR

[Guoxiong Li]

Hi all,

This patch implements the features about the `/jep` command and JEP bot. The detailed designs and discussions are listed at [1][2].

Thanks for taking the time to review.

Best Regards,
-- Guoxiong

[1] https://mail.openjdk.java.net/pipermail/skara-dev/2021-December/005481.html
[2] https://mail.openjdk.java.net/pipermail/skara-dev/2022-March/005770.html

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Commit messages:
 - Remove whitespace.
 - SKARA-1096: New command and label for JEPs, similar to CSR

Changes: https://git.openjdk.java.net/skara/pull/1297/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1297&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-1096
  Stats: 1326 lines in 19 files changed: 1306 ins; 0 del; 20 mod
  Patch: https://git.openjdk.java.net/skara/pull/1297.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1297/head:pull/1297

PR: https://git.openjdk.java.net/skara/pull/1297