RFR: 7903519 : jtreg/jtharness is missing features for basic crash testing [v6]

[andrlos]

> this does not exactly add a crash testing option, however it allows users to define their own resultModifiers that they can force jtharness to use via advertising their resultModifier service in META-INF. I tested it with basic crashOnlyModificator and it works as intended - allows me to correctly skip and pass all the regular failures and only leaves me with crash tests as failures. Perfect for corner cases like JVM testing and such.
> Also checked correct behavior in the logs, where the regular failure is still being reported and only the justification of the result modification is added at the bottom.

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

  more comment edits

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Changes:
  - all: https://git.openjdk.org/jtharness/pull/57/files
  - new: https://git.openjdk.org/jtharness/pull/57/files/da209eb1..46ff62a8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jtharness&pr=57&range=05
 - incr: https://webrevs.openjdk.org/?repo=jtharness&pr=57&range=04-05

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtharness/pull/57.diff
  Fetch: git fetch https://git.openjdk.org/jtharness.git pull/57/head:pull/57

PR: https://git.openjdk.org/jtharness/pull/57