RFR: bot: add profile handler

[Erik Helin]

Hi all,

please review this patch that adds a "profiling handler" typically listening on the `/profile` path. The profile handler will create a JFR recording that is sent as the reply to the HTTP request. The handler needs to configure a max duration (in seconds) for the recording and and a path to the `.jfc` configuration file. I made sure that only recording is allowed at a time to prevent too many requests to slow down the system too much.

Testing:
- [x] Tested locally on Linux x64 with various bots and configurations

Thanks,
Erik

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Commit messages:
 - bot: add profile handler

Changes: https://git.openjdk.java.net/skara/pull/1164/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1164&range=00
  Stats: 132 lines in 3 files changed: 131 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/1164.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1164/head:pull/1164

PR: https://git.openjdk.java.net/skara/pull/1164