[Gradle] Use platform classloader as parent in K2Native isolated class loader

[danysantiago]

Fixes KT-65761

[danysantiago]

Moving to draft... I was further testing and it seems ClassLoader.getPlatformClassLoader() is not available.? Is the JDK used to compile the plugin at least 9 or greater? I wouldn't like to use ClassLoader. getSystemClassLoader() even though that would also solve the issue...

[danysantiago]

Yup, the plugin is jvm target 8 so ClassLoader.getPlatformClassLoader() is not available (added in Java 9), I opted for removing the second null param of URLClassLoader so it uses the default parent, which should be the system class loader.

I guess the question is, is that OK? It sort of defeats the purpose of an 'isolated' class loader, not entirely but to some degree.

[dkrasnoff]

I guess the question is, is that OK? It sort of defeats the purpose of an 'isolated' class loader, not entirely but to some degree.

I'll run this branch against our integration tests to check that it is OK.

But to merge this PR you need to add an integration test for you fix. Here is readme how to do that.

[danysantiago]

Added an integration test, thanks for the hints @dkrasnoff.