Add License Usage Count Column to Licenses Screen

[msymons]

Current Behavior

The /licenses screen displays 489 licenses with SPDX License ID in v4.8.2 but gives no indication of whether any of these licenses are used..

Proposed Behavior

Add a License Usage Count column to the Licenses screen. ie, so that one can see at a glance that there are (say) 10,000 usages of Apache-2.0 and only 10 of Apache-1.0

The column should be sortable so that it is easy to inspect (say) the top 10 licenses in the portfolio.

There should also perhaps be a "none" row added to the licenses listing so that we can have a count of how many components have NO license declared.

The count that is displayed could later be turned into a link, at such time as DT component search is extended to include license search.

Checklist

• [X] I have read and understand the contributing guidelines
• [X] I have checked the existing issues for whether this enhancement was already requested