RFR: bot: add work item name to counters [v2]

[Erik Helin]

> Hi all,
> 
> please review this patch that adds a new label to the counters in `BotRunner` - `work-item`. The `work-item` label shows the name of the work item (in addition to the bot name which is already present in the `bot` label). This is useful for metrics from larger bots that consists of multiple work items.
> 
> Thanks,
> Erik

Erik Helin has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase.

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Changes:
  - all: https://git.openjdk.java.net/skara/pull/1169/files
  - new: https://git.openjdk.java.net/skara/pull/1169/files/2ff20b2b..2ff20b2b

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=skara&pr=1169&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=skara&pr=1169&range=00-01

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/skara/pull/1169.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1169/head:pull/1169

PR: https://git.openjdk.java.net/skara/pull/1169