Add a Docker image capable of running tests

[adambabik]

This change adds a new GHA workflow that runs tests in a Docker container. It appears as a new check but it's not required, for now.

Other changes:

• GoReleaser update
• Docker image release in GoReleaser config
• Moving of tests setup from Makefile entirely to Go

Closes https://github.com/stateful/runme/issues/605

[sonarcloud[bot]]

Quality Gate failed

Failed conditions
7 Security Hotspots

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