Improved multi platform support

[shawaj]

Currently our multi platform support is based around using lowest common denominator for building docker images. For example, building armv6 for armv6, armv6 and aarch64 based devices.

Whilst this works, we now need to support some other non-compatible arch types such as amd64 / x86_64 where this will not work.

Both balena and docker have ways of dealing with this kind of thing such as...

Docker:

• Build ARGs
• target platforms

Balena:

• Dockerfile templates and build variables
• container contracts

With some of these we can build different images for different architectures as well as pull in different ones for different builds, without maintaining multiple repos.

We need to investigate these in more detail and pull together a plan for multi arch support

[shawaj]

hm-miner multi architecture building using build ARGs and strategy matrix in github action NebraLtd/hm-miner#56

[shawaj]

I guess maybe using --profile with docker might help but not sure balena supports that

[shawaj]

Relates to #164

[shawaj]

relates to #11