RFR: CODETOOLS-7903008: JMH: Support incremental annotation processing for Gradle Java plugin [v2]

[Taylor Wicksell]

> This change adds support for Gradle's [incremental annotation processing](https://docs.gradle.org/current/userguide/java_plugin.html#sec:incremental_annotation_processing). Without this support, developers using the JMH annotation processor in their Gradle projects will see their compilation time increased due to Gradle invalidating its incremental compilation cache.

Taylor Wicksell has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  Adds support for Gradle's incremental annotation processing

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Changes:
  - all: https://git.openjdk.java.net/jmh/pull/43/files
  - new: https://git.openjdk.java.net/jmh/pull/43/files/fb9b5c01..436b4281

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmh&pr=43&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jmh&pr=43&range=00-01

  Stats: 19 lines in 7 files changed: 6 ins; 0 del; 13 mod
  Patch: https://git.openjdk.java.net/jmh/pull/43.diff
  Fetch: git fetch https://git.openjdk.java.net/jmh pull/43/head:pull/43

PR: https://git.openjdk.java.net/jmh/pull/43