RFR: 8367915: [TestBug] Add system property to ScreenCaptureTestWatcher [v2]

[Kevin Rushforth]

On Thu, 18 Sep 2025 14:32:24 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

>> Added `test.screenshot` system property to the `ScreenCaptureTestWatcher` to control writing of the screenshot data url to stderr.
>> 
>> Added corresponding gradle option `TEST_SCREENSHOT`.
>> 
>> The function is disabled by default for privacy reasons.
>
> Andy Goryachev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   firefox

Marked as reviewed by kcr (Lead).

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PR Review: https://git.openjdk.org/jfx/pull/1910#pullrequestreview-3240257331