feat(node): zfs monitor and grafana ui

## Installation
Add parameters:
- `zfs_exporter_enabled`: setup zfs_exporter on this node, false by default
- `zfs_exporter_version`: current `3.8.0`
- `zfs_exporter_port`:    zfs exporter listen port, 9134 by default
- `zfs_exporter_options`: see "/roles/node_monitor/defaults/main.yml"

## Prometheus
Add [node_exporter] (forked from [pdf-node_exporter]) with more metrics:
- `node:zfs:pool_metrics`
- `node:zfs:dataset_metrics`

Add alert rules:
- `ZPoolDegraded`
- `ZPoolFaulted`
- `ZPoolOffline`
- `ZPoolUnavail`
- `ZPoolRemoved`
- `ZPoolSuspended`
- `ZPoolReadonly`
- `ZPoolSpaceFull`
- `ZDatasetSpaceFull`

Update alert rule:
-  `NodeFsSpaceFull` with `fstype!="zfs"`

## Grafana
Add panels:
- [node-zfs.json]
  - list ZFS Pools and Datasets
  - unhealthy pool list fisrt
  - ability search with `Node ID`, `Pool`, `Dataset`
  - alert summary about zfs

Update panels:
- [node-overview.json](http://g.pigsty/d/node-overview/node-overview)
  - add `ZFS Pools` Row
  - unhealthy pool list fisrt
- [node-alert.json](http://g.pigsty/d/node-alert/node-alert)
  - show zfs alerts
  - cell link to [node-overview.json] page with pool name and/or dataset name filter

[node_exporter]: https://github.com/waitingsong/zfs_exporter
[pdf-node_exporter]: https://github.com/pdf/zfs_exporter
[node-overview.json]: http://g.pigsty/d/node-overview/node-overview

Author: waitingsong

files/grafana/node/node-alert.json

@@ -171,7 +171,7 @@
         "textMode": "auto",
         "wideLayout": true
       },
-      "pluginVersion": "11.1.3",
+      "pluginVersion": "11.5.2",
       "targets": [
         {
           "datasource": {
@@ -278,7 +278,7 @@
         "textMode": "auto",
         "wideLayout": true
       },
-      "pluginVersion": "11.1.3",
+      "pluginVersion": "11.5.2",
       "targets": [
         {
           "datasource": {
@@ -420,6 +420,7 @@
           "sort": "none"
         }
       },
+      "pluginVersion": "11.5.2",
       "targets": [
         {
           "datasource": {
@@ -827,6 +828,48 @@
                 ]
               }
             ]
+          },
+          {
+            "matcher": {
+              "id": "byName",
+              "options": "ZFS_Pool"
+            },
+            "properties": [
+              {
+                "id": "links",
+                "value": [
+                  {
+                    "title": "Node Instance: ${__data.fields.IP}",
+                    "url": "/d/zfs-overview/node-zfs?var-id=${__data.fields.IP}&${__url_time_range}&var-pool=${__data.fields.ZFS_Pool}"
+                  }
+                ]
+              },
+              {
+                "id": "custom.width",
+                "value": 100
+              }
+            ]
+          },
+          {
+            "matcher": {
+              "id": "byName",
+              "options": "ZFS_Dataset"
+            },
+            "properties": [
+              {
+                "id": "links",
+                "value": [
+                  {
+                    "title": "",
+                    "url": "/d/zfs-overview/node-zfs?var-id=${__data.fields.IP}&${__url_time_range}&var-pool=${__data.fields.ZFS_Pool}&var-dataset=${__data.fields.ZFS_Dataset}\r\n"
+                  }
+                ]
+              },
+              {
+                "id": "custom.minWidth",
+                "value": 120
+              }
+            ]
           }
         ]
       },
@@ -855,7 +898,7 @@
           }
         ]
       },
-      "pluginVersion": "11.1.3",
+      "pluginVersion": "11.5.2",
       "targets": [
         {
           "datasource": {
@@ -880,7 +923,9 @@
               "Time": true,
               "Value": false,
               "__name__": true,
-              "job": true
+              "job": true,
+              "metric_type": true,
+              "type": true
             },
             "indexByName": {
               "Time": 11,
@@ -901,6 +946,7 @@
             "renameByName": {
               "Value": "Silence",
               "Value #A": "Silence",
+              "__name__": "",
               "alertname": "Alert",
               "alertstate": "State",
               "category": "Category",
@@ -911,7 +957,11 @@
               "ip": "IP",
               "job": "",
               "level": "Level",
-              "severity": "Severity"
+              "metric_type": "ZFS_Metric_Type",
+              "name": "ZFS_Dataset",
+              "pool": "ZFS_Pool",
+              "severity": "Severity",
+              "type": "ZFS_Type"
             }
           }
         }
@@ -2740,7 +2790,7 @@
     }
   ],
   "revision": 1,
-  "schemaVersion": 39,
+  "schemaVersion": 40,
   "tags": [
     "Pigsty",
     "NODE",