Add Github short hash to all services

[posterzh]

Issue

• Link: gateway_mfr exited with a non-zero status hm-diag#352
• Summary:
  There are many Sentry issues related with "gateway_mfr exited with a non-zero status" in hm-diag.
  This is most likely happening if not all services get restarted when we release a new version to the Balena fleets.
  As a convention, we update the FIRMWARE_VERSION in the settings.ini in the every version update so that all services restart, but if we forget to update FIRMWARE_VERSION, then it is the case that only some services will restart.

It would be safer and better solution to add FIRMWARE_SHORT_HASH to the environment variable of all the services since its value is generated automatically on every release.

How
Add FIRMWARE_SHORT_HASH environment variable to packet-forwarder and helium-miner service.
The other services already contain this environment variable.

Screenshots

References

Checklist

• Tests added
• Cleaned up commit history (rebase!)
• Documentation added
• Thought about variable and method names