RFR: 8313613: Use JUnit in langtools/lib tests [v3]

[Qing Xiao]

> Use JUnit Jupiter API in langtools/lib tests instead of TestNG. They are under test/langtools/lib/combo/tools/javac/combo/.
> Modified tests that extend tools in CompilationTestCase and JavacTemplateTestBase to implement TestWatcher.

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

 - Merge pull request #1 from sormuras/pr/15281
   
   Cleanup conversion. Thanks Christian!
 - Cleanup conversion

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15281/files
  - new: https://git.openjdk.org/jdk/pull/15281/files/5f9f0f60..b4393108

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15281&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15281&range=01-02

  Stats: 290 lines in 13 files changed: 74 ins; 119 del; 97 mod
  Patch: https://git.openjdk.org/jdk/pull/15281.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15281/head:pull/15281

PR: https://git.openjdk.org/jdk/pull/15281