Define basic planning-related server status metrics for CBR. I'm thinking of the equivalents to these ones:

https://github.com/10gen/mongo/blob/4fc1de8141b668f5ffb5bb2d2a5f576e3e30766b/src/mongo/db/exec/classic/multi_plan.cpp#L86.

This includes adding CBR equivalents of these:

• query.multiPlanner.classicMicros
• query.multiPlanner.classicCount
• query.multiPlanner.histograms.classicMicros
• query.multiPlanner.histograms.classicWorks

Plus:

• We need to decide whether existing metrics should include CBR or they should be split out.
• We need to make a decision about how to count multiplanner metrics for the cases where MP is used but it falls back to CBR and CBR makes the planning decision.

This ticket should review all the MP serverstatus metrics and ensure they make sense after introducing CBR, and that we have equivalents for CBR.