feat(docker): add docker-compose file to run CI locally

[gustavovalverde]

Motivation

We'd like to allow developers to run CI locally easily, using a similar approach to how we run it in our GitHub Actions, but without having to remember each specific command needed to run a specific test.

This would allow developers to confirm if an issue is specific to GitHub or GCP, or if it also reflects locally, and allow them to debug it easier.

Fixes #4464
Fixes #7534
This sets the ground for #8023

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Complex Code or Requirements

• Needs docker-compose https://docs.docker.com/compose/install/

Solution

• Create a docker-compose.test.yml which can be used to run tests with a simple command
• Add a test.env file to avoid adding all these variables to the compose file.
• Create documentation on how to use CI locally

Testing

• Run at least one test locally following the provided documentation

Review

The whole @ZcashFoundation/devops-reviewers should at least try this.

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Follow Up Work