Fix toolchain support for non-java executables

[anthonyvdotbe]

#118 introduced toolchain support. However, due to the hard-coded "java", this doesn't work for non-java executables such as jlink (i.e. #148)

Fixes #148

[rcuprak]

I tested the fix and it corrects the blocking issue #148

[anthonyvdotbe]

@abhinayagarwal @jperedadnr will you please review? (mentioning you since you reviewed the original PR as well)

[alerosmile]

This should probably be added to other places where executable is still in use. Detecting the JDK home for preparePaths() does not work using toolchains.

[anthonyvdotbe]

@alerosmile the sole goal of this PR is to fix the regression introduced in #118 If you believe toolchain support is incomplete or should be improved, please file a new issue and/or PR instead.

[OmSarabeSolutions]

Yes this change fixes the goal javafx:jlink when using Toolchains.
Tested with java 22, javafx 23.
Can you merge it please ?

[anthonyvdotbe]

@jperedadnr @abhinayagarwal @johanvos would you mind merging and releasing a new version to Maven Central please? This is a trivial fix that has been confirmed to work by 2 different people.