build and push a 'use' image for each proposal

[turadg]

Problem to solve

Downstream integration tests rely on a synthetic state of Mainnet. For example, the upgrade-12 test in agoric-sdk.

While developing, it needs a branch that reflects the complete history of passed proposals. This repo publishes that as main (since #24)

However, once upgrade-12 itself passes and is incorporated into main, that test will begin to fail. Even though the proposal is done and passed, we shouldn't break the CI of the branch that tested it.

Design

So this repo should publish an image for using the chain after each proposal. (i.e. an image for each use-${proposalName} stage)

There should still be a main image because all the "use" images have a RUN that terminates (for use in tests) but we want to offer an image that developers can use to run the chain with the latest synthetic state of Mainnet.

[mhofman]

I am currently working around this by manually creating an upgrade-12 branch (and later upgrade-13) containing only the required layers, and using GH actions trigger to generate a tagged image.