Previously when Handler was creating a URL from a context URL and a
spec, any occurrances of /../ or /./ in the spec would be left as-is.
This differed from the JDK's Handler implementation which normalizes
the URL by modifying the path to remove any occurrences of /../ or
/./

This commit updates our Handler implementation to align it with the
JDK's. Tests have been added to assert that, given the same inputs,
the two Handler classes produce the same output.

Closes gh-9917