Previously, jars (either top-level or nested) in Zip64 format were
treated as normal jar files. This would lead to a failure later on
when an attempt was made to read an entry from the file.

This commit updates the loader to fail fast when it encounters a
Zip64 jar file. Such files are identified by the number of entries
in the central directory end record being 0xFFFF.

Closes gh-8735