Create a script to add missing tags to components

[ctrueden]

Some components in the SciJava ecosystem were/are released in a way that does not create a corresponding SCM tag. We need a script to check for that situation across all release versions of a given GA, and push new tags as needed.

This can easily be accomplished by extracting the Implementation-Build entry from the JAR manifest of each release artifact.

These tags are instrumental in the melting pot script's proper functioning.

[ctrueden]

The melting pot has heuristics now to get the source at the right tag, so we haven't had any real problems with this for many years. But it would still be nice to scan through old release JARs and make sure that there is a tag for every commit hash documented in them.