RFR: 8271170: Add unit test for what jpackage app launcher puts in the environment [v2]

[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.

Alexey Semenyuk has updated the pull request incrementally with one additional commit since the last revision:

  Handle duplicate elements in `java.library.path` system property value.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5056/files
  - new: https://git.openjdk.java.net/jdk/pull/5056/files/bda38d39..4c0891dd

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5056&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5056&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 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