Golangci lint fixes (#195)

* Add golangci-lin as make target
* Fix: could omit type ... from declaration; it will be inferred from the right-hand side (staticcheck)
* Fix func intArrayContains is unused (unused)
* Fix: could use strings.ReplaceAll instead (staticcheck)
* Fix: could expand call to math.Pow (staticcheck)
* Fix: could use tagged switch on `...` (staticcheck)
* Fix: Error return value of `...` is not checked (errcheck)
* Fix: ineffectual assignment to err (ineffassign)
* Fix: There is no need to wait for command completion
* Add cpustat, diskstat and schedstat config
* Use slices to exclude metrics
* Replaced stringArrayContains by slices.Contains
* Replace m[k]=v loop with maps.Copy
* Use module slices from the standard library. Remove use of golang.org/x/exp/slices
* Use SplitSeq and max to modernize code

example-configs/collectors.json

@@ -1,6 +1,19 @@
 {
     "cpufreq": {},
     "cpufreq_cpuinfo": {},
+    "cpustat": {
+        "exclude_metrics": [
+            "cpu_idle"
+        ]
+    },
+    "diskstat": {
+        "exclude_metrics": [
+            "disk_total"
+        ],
+        "exclude_mounts": [
+            "slurm-tmpfs"
+        ]
+    },
     "gpfs": {
         "exclude_filesystem": [
             "test_fs"
@@ -21,6 +34,8 @@
     },
     "numastats": {},
     "nvidia": {},
+    "schedstat": {
+    },
     "tempstat": {
         "report_max_temperature": true,
         "report_critical_temperature": true,
@@ -38,4 +53,4 @@
     "topprocs": {
         "num_procs": 5
     }
-}
+}