serverStatus should allow fine-grained metrics exclusion

Motivated by work on SERVER-63642, we would like to exclude some serverStatus metrics from FTDC collection. This is not possible with the current serverStatus command which only allows excluding top-level sections/keys from the output. The result of implementing this task is that we would be able to exclude arbitrarily nested elements from the metrics output.

Before this change, serverStatus() accepts an argument which excludes top-level sections, eg

{replication: false}

. this change allows detailed exclusion of metrics, eg

{metrics: {query: {multiPlanner: {histograms: false}}}}

. both individual fields/metrics and objects/branches can be excluded