RFR: 7903479: JMH: Add .editorconfig so IDEs would pick up the common settings automatically: indent, trim whitespace

[Vladimir Sitnikov]

See https://bugs.openjdk.org/browse/CODETOOLS-7903479

I tried re-format random files from JMH, and they either kept intact, or the changes were minimal.

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Commit messages:
 - 7903479: JMH: Add .editorconfig so IDEs would pick up the common settings automatically: indent, trim whitespace

Changes: https://git.openjdk.org/jmh/pull/105/files
 Webrev: https://webrevs.openjdk.org/?repo=jmh&pr=105&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903479
  Stats: 52 lines in 2 files changed: 52 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jmh/pull/105.diff
  Fetch: git fetch https://git.openjdk.org/jmh.git pull/105/head:pull/105

PR: https://git.openjdk.org/jmh/pull/105