Start script should be robust to errors

[shawaj]

The startup script is currently brittle because it is written in bash. Rewriting with python will make it more robust to failures.

Original notes: convert the startup script to python and use the helper functions in hm-pyhelper for the functions there There isn't much to do here.

• get and check ecc bus
• start helium_gateway binary

Acceptance criteria

• Script is converted into a python module that can be executed with python MODULE_NAME.
• Test directory not included in module src
• File deletion handled in Dockerfile instead (eg don't copy in the first place)
• i2dection/ecc uses a pyhelper method
• Errors sent to sentry
• Use Tenacity library for retry logic
• Script is successful if gateway starts as a result
• Update README accordingly
• Log failures and exit details when helium_gateway terminates
• Python src linter added to workflow
• remove 'v' from the version string. dpkg -s doesn't show that.

[pritamghanghas]

@shawaj old miner was using .sh. Do we want to convert it only for getting variant information? At this stage I see only thing that can come from there is i2c bus. This can be made available through docker env as well, gen_docker_compose already knows about the bus.