Minimise import statements in jpackage sources

It was pointed out in review that several files (e.g., Arguments.java) have unused imports that can be removed.
Except for wildcard static imports, we should replace the wild-card imports with explicit imports.
for example:
src/jdk.jpackage/linux/classes/jdk/jpackage/internal/LinuxDebBundler.java (java.util.* and java.io.*)