RFR: 8296330: Tests: Add layout container snapping tests [v2]

[Ambarish Rapte]

On Tue, 8 Nov 2022 20:38:33 GMT, Marius Hanl <mhanl at openjdk.org> wrote:

>> could you please create an umbrella ticket listing all the types that need to be added to the test and/or fixed?
>> 
>> here is an example of such ticket (with an umbrella unicode):
>> [JDK-8241364](https://bugs.openjdk.org/browse/JDK-8241364)
>
> created https://bugs.openjdk.org/browse/JDK-8296609

Should this list include the class `Region` and `FlowPane` too? I see these classes use non-snapped insets.

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PR: https://git.openjdk.org/jfx/pull/936