RFR: 8315406: [REDO] serviceability/jdwp/AllModulesCommandTest.java ignores VM flags

[Leonid Mesnik]

The fix changes test serviceability/jdwp/AllModulesCommandTest.java to accept VM flags. 
1) The 'ProcessTools.createTestJvm(JDWP_OPT, DEBUGGEE);'  is used to start debugee
2) The stderr is just logging and tests doesn't check if it is empty. stderr might contain some VM output which doesn't mean failure
3) Some refactoring is done. Method ' public void onStringRead(StreamHandler handler, String line) {' doesn't need to check which handler is used and corresponding code and methods are deleted. The field 'inputHandler' and 'errorHandler' were moved into method.

Tested with tier1-5 to ensure that test correctly work with CI options.

The serviceability/jdwp/AllModulesCommandTest.java is the only one test in serviceability/jdwp directory so no other tests should be affected.

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Commit messages:
 - 8315406

Changes: https://git.openjdk.org/jdk/pull/15544/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15544&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315406
  Stats: 63 lines in 3 files changed: 3 ins; 51 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/15544.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15544/head:pull/15544

PR: https://git.openjdk.org/jdk/pull/15544