Use perflib to gather metrics in the mssql collector

The perflib-based access code replaces WMI and is substantially more efficient
and stable, leading to fewer collection timeouts in the mssql collector.

Signed-off-by: Michael Allen <MAllen@laserfiche.com>

collector/collector.go

@@ -58,6 +58,10 @@ var (
 
 func registerCollector(name string, builder collectorBuilder, perfCounterNames ...string) {
 	builders[name] = builder
+	addPerfCounterDependencies(name, perfCounterNames)
+}
+
+func addPerfCounterDependencies(name string, perfCounterNames []string) {
 	perfIndicies := make([]string, 0, len(perfCounterNames))
 	for _, cn := range perfCounterNames {
 		perfIndicies = append(perfIndicies, MapCounterToIndex(cn))