RFR: 7903720: Change layout of jextract image [v5]

[Maurizio Cimadamore]

On Tue, 30 Apr 2024 17:14:35 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> See JBS issue for problem description.
>> 
>> This patch changes the layout of the jextract image we produce. The new image has the 2 launcher scripts in the root of the image, with a nested `runtime` folder containing the jlink runtime image.
>> 
>> I've added both launcher scripts to the repo under the `src/main` directory, and they are copied to the image during the build. The script is somewhat simplified by removing a blank variable that was not being used. I also took the opportunity to address an issue with the windows launcher script turning off `echo`. Instead it now avoids output using the `@` prefix for each command in the script.
>> 
>> I've tested that the scripts work (using `jextract --help`) on both Linux and Windows.
>
> Jorn Vernee has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - disable macos runs pt2
>  - disable macos runs

Marked as reviewed by mcimadamore (Reviewer).

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PR Review: https://git.openjdk.org/jextract/pull/241#pullrequestreview-2032144800