docs: Explain how testing and CI works in more detail

[auxesis]

• Add steps describing how to do local development
• Add steps for installing mise
• Add section explaining project layout
• Add explanation of what we're testing, and how changes trigger tests in CI
• Add steps describing how to run tests for different Postgres versions
• Add feedback at the end of mise run build that tells the user where to find build artifacts

[cisopaul]

This looks good for the 'how do I do this?' view, but there is likely more detail needed for the 'what does this system look like & why are certain things true' view. For example what is mise used for & what tests are being run?

Merging this now is ok, but I think we'll need a bit more detail somewhere to match what we have here: https://github.com/cipherstash/cipherstash-suite/blob/main/docs/diagrams/console-api-releases.drawio.svg

[cisopaul]

Is there an arch diagram of what this looks like?

[cisopaul]

Also ref this comment on line 394 for the release component

[auxesis]

Should be addressed in 7aca897.

[auxesis]

This looks good for the 'how do I do this?' view, but there is likely more detail needed for the 'what does this system look like & why are certain things true' view. For example what is mise used for & what tests are being run?

This is good feedback, thanks @cisopaul.

I have added docs explaining the project layout:

I have added docs explaining what the tests are testing:

I have added a diagram explaining how the testing works:

[cisopaul]

This section is really good. We should try to use this in the other places.