RFR: 8253878: clean up nsk/share/jvmti/ArgumentHandler

[Igor Ignatyev]

Hi all,

could you please review this small patch which reformats `ArgumentHandler`, removes unused
`findOptionStringValue(String name, String defaultValue)` method, fixes typos?

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Commit messages:
 - 8253878: clean up nsk/share/jvmti/ArgumentHandler

Changes: https://git.openjdk.java.net/jdk/pull/443/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=443&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253878
  Stats: 43 lines in 1 file changed: 1 ins; 25 del; 17 mod
  Patch: https://git.openjdk.java.net/jdk/pull/443.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/443/head:pull/443

PR: https://git.openjdk.java.net/jdk/pull/443