feat(docker): sapphire: reduce docker layers + 0.6.4 mainnet

[CedarMist]

Upgrades the sapphire-dev container to 0.6.4 versus 0.6.4-testnet

The Dockerfile has been reorganized:

• Reduce the number of layers by combining commands
• Remove downloaded tar files and unused extracted files

Additionally start.sh, when used with the mock backend, will increment the epoch every 10 minutes - now queries current epoch before advancing, instead of fetching once and incrementing regardless of other things advancing the epoch.

This reduces the docker image size by approx 125mb

[codecov]

Codecov Report

Merging #463 (2a410d6) into main (e7c5045) will not change coverage.
Report is 1 commits behind head on main.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #463   +/-   ##
=======================================
  Coverage   62.03%   62.03%           
=======================================
  Files          37       37           
  Lines        3909     3909           
=======================================
  Hits         2425     2425           
  Misses       1276     1276           
  Partials      208      208           

[ptrus]

👍
Too bad there's still no CI that would test the image

[CedarMist]

@ptrus We can talk next week about the bigger picture of testing & circular dependencies etc. and how to untangle.