software/grafana: include a telegraf plugin to get slapos process metrics

For now this still have to be enabled with a config like this in a .conf
file in srv/telegraf/extra-config/  :

    [[inputs.execd]]
      name_override = "slapos"
      # this needs sudo when using can not access supervisor socket, like when being installed in root slapos
      command = ["/usr/bin/sudo", "$SOFTWARE_DIR/go.work/bin/telegraf-input-slapos", "-config", "/path/to/slapos.conf"]

/path/to/slapos.conf would contain something like this:

    [[inputs.slapos]]
      ## Folder where partitions are located
      instance_root = "/srv/slapgrid/"

      ## filepath.Glob pattern to look for recursive instances
      recursive_instance_glob_pattern = "*/srv/runner/inst*/"

      ## Path of supervisor socket, relative to instance root
      socket_name = "sv.sock"

software/grafana/software.cfg

@@ -55,6 +55,11 @@ go.importpath = github.com/influxdata/telegraf
 repository    = https://github.com/influxdata/telegraf
 revision      = v1.19.1-0-g9f8be047
 
+[go_github.com_perrinjerome_slapos_telegraf_input]
+<= go-git-package
+go.importpath = github.com/perrinjerome/telegraf-input-slapos
+repository    = https://github.com/perrinjerome/telegraf-input-slapos
+revision      = v0.0.1-0-gf8981f3
 
 [gowork]
 install =
@@ -63,6 +68,7 @@ install =
   ${go_github.com_grafana_loki:location}:./cmd/logcli
   ${go_github.com_influxdata_telegraf:location}:./cmd/...
   ${go_github.com_influxdata_influxdb:location}:./cmd/...
+  ${go_github.com_perrinjerome_slapos_telegraf_input:location}:./...
 
 # disable cgo, to prevent loki/promtail from using go-systemd
 environment =