RFR: 8366678: Use JUnit in test/langtools/tools/javac [v4]

[Christian Stein]

> Please review this change to use JUnit in tests of `test/langtools/tools/javac`.
> 
> ### Assess Status Quo
> A local `make test TEST=test/langtools/tools/javac` run before the conversion yields:
> 
> Test results: passed: 3,938; excluded: 4; did not match keywords: 2; did not meet platform requirements: 2
> Framework-based tests: 3043 = 2762 TestNG + 281 JUnit
> 
> 
> ### Perform Automatic Conversion
> - [junit-convert](
> https://github.com/lahodaj/netbeans/tree/openjdk-testng-junit-fixes-and-hacks/java/java.openjdk.project/junit-convert)
> 
> ### Perform Manual Adjustments
> 
> Some of the following adjustments will be integrated into the `junit-convert` tool.
> 
> #### Make argument source factory method `static`
> 
> Method 'public java.lang.Object[][] org.openjdk.tests.javac.FDTest.caseGenerator()'
>   must be static: local factory methods must be static
>   unless the PER_CLASS @testinstance lifecycle mode is used;
>   external factory methods must always be static.
> 
> 
> #### Make `@AfterAll`-annotated method `static`
> 
> [ERROR] @afterall method 'public void org.openjdk.tests.vm.FDSeparateCompilationTest.cleanupCompilerCache()'
>   must be static unless the test class
>   is annotated with `@TestInstance(Lifecycle.PER_CLASS)`.
> 
> 
> #### Remove `static` modifier from `@Test`-annotated methods
> This configuration error should have been detected by JUnit Jupiter and reported via the Discovery
> Issues API: https://docs.junit.org/current/user-guide/#running-tests-discovery-issues
> 
> #### Rename test property to `JUnit.dirs`
> 
> package org.junit.jupiter.api does not exist
> 
> 
> #### Add custom test instance factory
> 
> Class [FDTests] must declare a single constructor
> Class [MethodReferenceTestKinds] must declare a single constructor
> 
> 
> ### Results
> Re-run tests via `make test TEST=test/langtools/tools/javac` after the conversion; yielding:
> 
> Test results: passed: 3,939; excluded: 4; did not match keywords: 2; did not meet platform requirements: 2
> Framework-based tests: 3043 = 0 TestNG + 3043 JUnit

Christian Stein has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Restore comment - it is unrelated to the JUnit conversion
 - Update to use correct library directories
   
   See also: https://openjdk.org/jtreg/faq.html#how-do-i-find-the-path-for-the-testng-or-junit-jar-files
 - 8361950: Set required version to 8+2
 - 8361950: Update to use jtreg 8

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27046/files
  - new: https://git.openjdk.org/jdk/pull/27046/files/839b9312..431eb75a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27046&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27046&range=02-03

  Stats: 44 lines in 12 files changed: 11 ins; 19 del; 14 mod
  Patch: https://git.openjdk.org/jdk/pull/27046.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27046/head:pull/27046

PR: https://git.openjdk.org/jdk/pull/27046