RFR: 8313612: Use JUnit in lib-test/jdk tests [v4]

[Qing Xiao]

> Modified all tests under lib-test/jdk to use JUnit

Qing Xiao has updated the pull request incrementally with three additional commits since the last revision:

 - Update test/lib-test/jdk/test/lib/hexdump/ObjectStreamPrinterTest.java
   
   Co-authored-by: liach <7806504+liach at users.noreply.github.com>
 - Update test/lib-test/jdk/test/lib/hexdump/HexPrinterTest.java
   
   Co-authored-by: liach <7806504+liach at users.noreply.github.com>
 - Update test/lib-test/jdk/test/lib/format/ArrayDiffTest.java
   
   Co-authored-by: Christian Stein <sormuras at gmail.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15131/files
  - new: https://git.openjdk.org/jdk/pull/15131/files/e520735d..7043c900

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15131&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15131&range=02-03

  Stats: 3 lines in 3 files changed: 0 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15131.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15131/head:pull/15131

PR: https://git.openjdk.org/jdk/pull/15131