Superbuild archive naming convention

The current naming convention for superbuild archives is SuperBuild-archives-MAJOR.MINOR.tar.bz2 for non patch releases and SuperBuild-archives-MAJOR.MINOR.PATCH.tar.bz2 for patch releases, although this is not always applied correctly for patch releases, for instance the archive for OTB 6.6.1 is SuperBuild-archives-6.6.tar.bz2 (probably because the archive has not changed).

This adds unnecessary struggles in deployment scripts/dockerfiles/whatnot using the Superbuild archive because the patch release case should be handled.

I propose to use the same convention SuperBuild-archives-MAJOR.MINOR.PATCH.tar.bz2 for all releases to simplify things.

For backward compatibility we could create symlinks SuperBuild-archives-MAJOR.MINOR.tar.bz2 pointing to SuperBuild-archives-MAJOR.MINOR.PATCH.tar.bz2 for existing releases.