docs: Add build script to test templates

[sdankel]

Description

Closes #3026

Adds a build script to the test templates that runs prior to the tests when cargo test is run. This makes it so users who copy this template don't have to run forc build prior to cargo test

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.

[K1-R1]

This is a really nice addition, just a few nits