POM: tweak repositories comment
POM: bump to pom-fiji 5.0

This updates to the latest SciJava software components.

It also uses release versions for all Fiji components.

Lastly, it removes the "artifacts which we would like included with
Fiji regardless of whether any Fiji plugin depends on them directly.
They have moved to the POM of sc.fiji:fiji, where they fit better.
POM: tidy up order of configuration blocks

Accomplished using:

    mvn tidy:pom