[crac] RFR: Convert CRaC tests from shell scripts to Java [v2]

[Radim Vansa]

> Right now this is a draft as it builds on top of https://github.com/openjdk/crac/pull/47
> 
> Please see `CracTest` javadoc for detailed info.

Radim Vansa has updated the pull request incrementally with one additional commit since the last revision:

  Some other improvements and fixes

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

Changes:
  - all: https://git.openjdk.org/crac/pull/50/files
  - new: https://git.openjdk.org/crac/pull/50/files/3cfa1cf0..ea9debd3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=crac&pr=50&range=01
 - incr: https://webrevs.openjdk.org/?repo=crac&pr=50&range=00-01

  Stats: 81 lines in 4 files changed: 43 ins; 25 del; 13 mod
  Patch: https://git.openjdk.org/crac/pull/50.diff
  Fetch: git fetch https://git.openjdk.org/crac pull/50/head:pull/50

PR: https://git.openjdk.org/crac/pull/50