RFR: 8302267: [jittester] Improve separation of test generation and execution [v2]

[Evgeny Nikitin]

> Please review a set of improvements that should improve working with other fuzzing generators and usage of JitTesterDriver with tests generated not by the JITTester:
> 
> - Provide better separation of individual test generation from java file writing, compiling, executing, etc.;
> - Introduce distinct Phases of the generation process (Generation, Compilation, GoldRun and VerificationRun);
> - Extract JItTesterDriver headers generation so that it would be possible to provide other header generators;
> - Introduce error tolerance to not get distracted by OOMEs, intrinsics missing in the compiled code, etc.;
> - Make it possible to specify time limit for an individual test generation;
> - Give better control over temp/workdir creation and cleaning;
> - Unify external process running;
> - Introduce UTF-8 support in external processes' output and human-readable escaping of it;

Evgeny Nikitin has updated the pull request incrementally with one additional commit since the last revision:

  Ignore large files

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12527/files
  - new: https://git.openjdk.org/jdk/pull/12527/files/417e05d7..0d1543a7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12527&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12527&range=00-01

  Stats: 98 lines in 5 files changed: 77 ins; 8 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/12527.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12527/head:pull/12527

PR: https://git.openjdk.org/jdk/pull/12527