This fixes an issue where filenames containing a period that aren't a
group ID, such as some-jar.12.jar, would be mistakenly be reported as
having the name "12" by syft, instead of the name "some-jar.12".
It works by testing whether the parts of the filename split on "."
are all valid Java identifiers.
Signed-off-by: Will Murphy <will.murphy@anchore.com>