Previously, if a class was added and then changed, a restart would be triggered
and things would behave as if the class had been deleted. This occurred
because, when looking for additional classes that were not on the original
classpath, only files that had been added were considered. The subsequent
change to the class was noticed as a modified rather than an addition,
resulting in the class being skipped.

This commit updates the resource resolver to only ignore deleted files and
consider both added files and modified files when looking for additional
resources.

Closes gh-14205