feat(nargo): add test to example noir program

[TomAFrench]

Related issue(s)

Related to noir-lang/docs#34. We'll likely want to give an example test for users to run without them having to write it themselves.

Description

Summary of changes

I've updated the value of EXAMPLE to include a test which will be tested by nargo test.

At the same time, I noticed that we always insert a compiler version of 0.1.0 into the Nargo.toml. I've changed this to pull the version from cargo.

Dependency additions / changes

Test additions / changes

Checklist

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt with default settings.
• I have linked this PR to the issue(s) that it resolves.
• I have reviewed the changes on GitHub, line by line.
• I have ensured all changes are covered in the description.

Documentation needs

• This PR requires documentation updates when merged.

Additional context