issue #23965: dashboard-lite

A stab at the question, "what dashboards can we give to our customers that would not require a serious long-term maintenance investment?"

A reworking of the first draft of nvd3 charts. With the difference that they are optimized for large data sets by just filtering aggressively down to a small working set of data. For serious BI, customers will need to invest in our complete solution.

The other fancy part of the code is to put the dashboards in their own module, as Jeff has already done for the serious dashboard.

These charts will only appear of the DashboardLite metric is set to true. This will allow us both to pilot this stab on a case-by-case basis, and provides a convenient mechanism for "real BI" to automatically turn of this "BI-lite" upon installation.