RFR: 8365262: [IR-Framework] Add simple way to add cross-product of flags [v6]

[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 one additional commit since the last revision:

  Improvements prompted by Emanuel

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Changes:
  - all: https://git.openjdk.org/jdk/pull/26762/files
  - new: https://git.openjdk.org/jdk/pull/26762/files/273e5f64..7bab7759

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26762&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26762&range=04-05

  Stats: 85 lines in 2 files changed: 62 ins; 15 del; 8 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