RFR: bots: add workItemName method

[Erik Helin]

Hi all,

please review this patch that adds the `WorkItem.workItemName` method. Some bots have several different kinds of work items and it can be useful for monitoring systems to distinguish these work items. I opted for the `workItemName` instead of just `name` since the `Bot` interface already has a `name` method and a number of classes implement both the `Bot` and `WorkItem` interfaces (common for smaller bots).

Thanks,
Erik

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Commit messages:
 - bots: add workItemName method

Changes: https://git.openjdk.java.net/skara/pull/1168/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1168&range=00
  Stats: 150 lines in 30 files changed: 150 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/skara/pull/1168.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1168/head:pull/1168

PR: https://git.openjdk.java.net/skara/pull/1168