RFR: 8365262: [IR-Framework] Add simple way to add cross-product of flags [v5]

[Manuel Hässig]

> This PR adds the `TestFramework::addCrossProductScenarios` method to enable more ergonomic testing of the combination of all flag combinations. To illustrate its use, I also converted one test to use the new cross product functionality.
> 
> Testing:
>  - [x] Github Actions
>  - [x] tier1,tier2 plus some internal testing on Oracle supported platforms

Manuel Hässig has updated the pull request incrementally with three additional commits since the last revision:

 - Fix test
 - Better counting in tests
 - post processing of flags and documentation

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26762/files
  - new: https://git.openjdk.org/jdk/pull/26762/files/f59e9d9d..273e5f64

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26762&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26762&range=03-04

  Stats: 65 lines in 2 files changed: 41 ins; 8 del; 16 mod
  Patch: https://git.openjdk.org/jdk/pull/26762.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26762/head:pull/26762

PR: https://git.openjdk.org/jdk/pull/26762