RFR: CODETOOLS-7903560: JMH: async profiler reports only the last fork result [v2]

[Jonas Konrad]

> Without this change, async-profiler would write the same result in each fork, overwriting the previous result.
> 
> This patch introduces a new "FileResult" class that collects the output paths of each benchmark. In `afterTrial`, the output files are moved to a new path that includes the pid (fork number would be an alternative but it's not as easily available).
> 
> At the moment, results of different runs are not coalesced. But with these changes, it would be easy to coalesce at least the results of the "collapsed" output mode. I plan to do this in another PR.

Jonas Konrad has updated the pull request incrementally with one additional commit since the last revision:

  address review

-------------

Changes:
  - all: https://git.openjdk.org/jmh/pull/121/files
  - new: https://git.openjdk.org/jmh/pull/121/files/ea8bb50a..177d78d5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jmh&pr=121&range=01
 - incr: https://webrevs.openjdk.org/?repo=jmh&pr=121&range=00-01

  Stats: 14 lines in 3 files changed: 7 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jmh/pull/121.diff
  Fetch: git fetch https://git.openjdk.org/jmh.git pull/121/head:pull/121

PR: https://git.openjdk.org/jmh/pull/121