To overcome command length limits on Windows, IntelliJ IDEA may launch
an application with a single jar on the classpath that contains that
application's actual classpath in the Class-Path attribute of its
manifest. This would prevent DevTools restarts from working as it
only considered the single jar's URL when identifying changeable URLs
and ignored the URLs added to the classpath via the jar's manifest.

This commit updates ChangeableUrls when it is created from a
URLClassLoader to consider the Class-Path manifest attribute of any
jars in the class loader's URLs. This allows the full classpath to
be considered when identifying URLs that are changeable and that
need to be monitored for restart triggering.

Closes gh-5127