Mimir integration

[gsanchietti]

⚠️ The PR has been tested and should work in common scenarios.
Waiting the release of new my.nethesis.it before releasing

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This pull request new features inside monitoring and alerting system:

• it adds a script (ns-plug-alert) to send alerts to the new implementation of my.nethesis.it using alertmanager format
• it fixes netdata configuration update

To test, setup the URL and credentials:

uci set ns-plug.config.my_url=https://qa.my.nethesis.it
uci set ns-plug.config.my_system_key=NETH-F5D2-5E69-A174-45A9-B1AB-2BB9-xxxx-xxxx
uci set ns-plug.config.my_system_secret=my_f620a0c63a99161021aa.21af8bffebd96356a6e7bbdee67321ba4bexxxxx
uci commit

Then:

ns-plug-alert fire --alertname DiskSpaceCritical --severity critical   --labels service=storage mountpoint=/mnt/data   --annotations     "summary_en=Disk space critical"     "summary_it=Spazio disco critico"     "description_en=Disk usage above 90% on /mnt/data"     "description_it=Utilizzo disco sopra 90% su /mnt/data"

ns-plug-alert resolve --alertname DiskSpaceCritical --severity critical   --labels service=storage mountpoint=/mnt/data   --annotations     "summary_en=Disk space critical"     "summary_it=Spazio disco critico"     "description_en=Disk usage above 90% on /mnt/data"     "description_it=Utilizzo disco sopra 90% su /mnt/data"
{"status": "success", "message": "Alert 'DiskSpaceCritical' resolved"}