Previously, RandomAccessDataFile used a semaphore and acquired it
interruptibly. This meant that an interrupted thread was unable to
access the file. Notably, this would prevent LaunchedURLClassLoader from
loading classes or resources on an interrupted thread.

The previous commit (937f8576) updates RandomAccessDataFile to acquire
the semaphore uninterruptibly. This commit adds a test to
LaunchedURLClassLoader to verify that it can now load a resource from
an interrupted thread.

Closes gh-6683