Configure -H:Path in native tests

[kkriske]

Is your feature request related to a problem? Please describe.
Allow configuration of the -H:Path option for running unit tests in native image.
My use-case has multiple native test runs with different builder options. Specifically, it gives the option to unpack the native library that's required at runtime during the build. So in the end, depending on the build configuration there will be additional files next to the executable.
So for multiple native-test configurations to not interfere, they ideally would be isolated in separate directories.
-H:Path is now hardcoded to the target folder (in maven at least), so I'd like to be able to specify a subdirectory for this.

Describe the solution you'd like
A way to configure the -H:Path option to be used from the plugin <configuration> block.

Describe alternatives you've considered
For now we need to rely on the declaration order of the configurations, to run the config that does not create these additional files first. This requires extra care as test executions should normally not interfere with each other.