Move org.scijava.usage to net.imagej.usage

Usage statistics are a contentious topic so they should not be stored in
the low-level SJC component. This move aggregates all usage-related
classes to a single component.
Update package references

Replaced org.scijava.usage with net.imagej.usage imports.

org.scijava.usage will be removed, in favor of consolidation within this
component.
Bump parent pom version

Updated pom-imagej version to 2.46.