collectd: add cgroup v2 config

Ubuntu 22 has cgroup v2 config by default

https://rootlesscontaine.rs/getting-started/common/cgroup2/#checking-whether-cgroup-v2-is-already-enabled
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html
https://man7.org/training/download/splc_cgroups_v1_slides.pdf

src/collectd/app_cgroup_v2.ejs

@@ -0,0 +1,42 @@
+LoadPlugin "table"
+<Plugin table>
+  <Table "/sys/fs/cgroup/docker/<%= containerId %>/memory.stat">
+    Instance "<%= appId %>-memory"
+    Separator " \\n"
+    <Result>
+      Type gauge
+      InstancesFrom 0
+      ValuesFrom 1
+    </Result>
+  </Table>
+
+  <Table "/sys/fs/cgroup/docker/<%= containerId %>/memory.max">
+    Instance "<%= appId %>-memory"
+    Separator "\\n"
+    <Result>
+      Type gauge
+      InstancePrefix "max_usage_in_bytes"
+      ValuesFrom 0
+    </Result>
+  </Table>
+
+  <Table "/sys/fs/cgroup/docker/<%= containerId %>/cpu.stat">
+    Instance "<%= appId %>-cpu"
+    Separator " \\n"
+    <Result>
+      Type gauge
+      InstancesFrom 0
+      ValuesFrom 1
+    </Result>
+  </Table>
+</Plugin>
+
+<Plugin python>
+  <Module du>
+    <Path>
+        Instance "<%= appId %>"
+        Dir "<%= appDataDir %>"
+    </Path>
+  </Module>
+</Plugin>
+