Selectable time range in the analytics page

The analytics web page https://cms-http-group.web.cern.ch/cms-http-group/analytics.html should allow us to specify the time range of the shown statistics.

This would allow people to "zoon in/out" and to also see the overview of the statistics along the years.

Start by reviewing the analytics generator and the published analytics.html page; the issue does not name repository files, tests, or an entry point. Trace how statistics are produced and rendered, then define a time-range interaction that supports zooming and multi-year overviews. Done means the page can display statistics for a selected range.

Written by the indexing model from the issue text.