RFR: 8271170: Add unit test for what jpackage app launcher puts in the environment

[Alexey Semenyuk]

Added jtreg test to verify jpackage launcher adds app dir to `java.library.path` system property.
Removed unused test/jdk/tools/jpackage/apps/installer/Hello.java.
Moved test/jdk/tools/jpackage/apps/image/Hello.java to test/jdk/tools/jpackage/apps/Hello.java.

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Commit messages:
 - dummy commit
 - Whitespace clean up
 - 8271170: Add unit test for what jpackage app launcher puts in the environment

Changes: https://git.openjdk.java.net/jdk/pull/5056/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5056&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271170
  Stats: 342 lines in 7 files changed: 212 ins; 116 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5056.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5056/head:pull/5056

PR: https://git.openjdk.java.net/jdk/pull/5056