RFR: 7903451: JMH: Refactor internal Optional usages [v3]

[Andrei Rybak]

> This is a follow-up to the email https://mail.openjdk.org/pipermail/jmh-dev/2023-January/003562.html
> 
> `java.util.Optional` isn't `Serializeable`. Because of that `org.openjdk.jmh.runner.options.TestOptions` fails with `java.io.NotSerializableException: java.util.Optional`, when  `org.openjdk.jmh.util.Optional` is completely replaced with `java.util.Optional`. See [test results on branch `java-util-optional`](https://github.com/rybak/jmh/actions/runs/4326921418), ([one commit](https://github.com/rybak/jmh/commit/25b9cb382be7285a51446976247d036ac855fc91) on top of initial state of this PR).
> 
> I didn't look further into possibility of removing `Optional`s as fields of class `CommandLineOptions`. I think that the refactoring up until the drop-in replacement to `java.util.Optional` might still be worth it, at least from the point of making it more approachable for people who are familiar with `java.util.Optional`.  So here are these changes for your consideration. Details are in the commit messages.

Andrei Rybak has updated the pull request incrementally with two additional commits since the last revision:

 - fixup! Runner: replace orAnother() with orElseGet()
   
   Indentation in Runner.java
 - fixup! Runner: replace orAnother() with orElseGet()
   
   Ternary operator code style in orElseGet()

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

Changes:
  - all: https://git.openjdk.org/jmh/pull/98/files
  - new: https://git.openjdk.org/jmh/pull/98/files/1e847757..e7547c8c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jmh&pr=98&range=02
 - incr: https://webrevs.openjdk.org/?repo=jmh&pr=98&range=01-02

  Stats: 5 lines in 2 files changed: 1 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jmh/pull/98.diff
  Fetch: git fetch https://git.openjdk.org/jmh.git pull/98/head:pull/98

PR: https://git.openjdk.org/jmh/pull/98