If the compiler runtime JDK is 9+,
it will already contain JrtFileSystemProvider and won't use provided
classloader
In order to fix KT-57154 we need to provide "java.home" argument to
newFileSystem
In order to reduce the severity of the leak in KT-56789 we cache
instances of FileSystem itself forever
Otherwise, each invocation of newFileSystem on JDK 9+ will leak
classloader, which is created deep inside the JDK code
Add unit test for JRT-FS contents served through CoreJrtFs
Add Gradle Integration test to
test if the daemon correctly reads JDK contents from the specified
toolchain and not from its runtime JDK
^KT-57154
Regression test for ^KT-57077
Simon Ogorodnik
ae32eff543