feat: build oasis-node and oasis-net-runner from source

[CedarMist]

@abukosek if you're interested, this change builds oasis-core from source rather than pulling from github releases

I think we should have the option to build Sapphire paratime binary from source too as it will make testing changes quicker.

However, I think there should probably be two modes:

• release mode - uses files downloaded from github releases
• dev mode - builds everything from source

Will investigate if this is possible.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.86%. Comparing base (aa3c5a1) to head (588503f).
Report is 182 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #485   +/-   ##
=======================================
  Coverage   61.86%   61.86%           
=======================================
  Files          37       37           
  Lines        3920     3920           
=======================================
  Hits         2425     2425           
  Misses       1288     1288           
  Partials      207      207           

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[abukosek]

Cool!
Yeah, I also think there should be two separate modes for this. The simplest way to do this would be to add another ENV var and then conditionally build from source or download existing artifacts based on that (or even better, an ARG, which we could then specify when building the image with --build-arg).

[matevz]

Superseeded by #601