docs: Add build script to test templates (#6510)

## Description

Closes https://github.com/FuelLabs/sway/issues/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](https://github.com/FuelLabs/devrel-requests/issues/new/choose)
- [ ] 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](https://github.com/FuelLabs/rfcs/blob/master/text/code-standards/external-contributors.md).
- [ ] I have requested a review from the relevant team or maintainers.

---------

Co-authored-by: K1-R1 <77465250+K1-R1@users.noreply.github.com>
Co-authored-by: Joshua Batty <joshpbatty@gmail.com>

templates/sway-script-test-rs/template/build.rs

@@ -0,0 +1,7 @@
+//! This build script is used to compile the sway project using `forc` prior to running tests.
+
+use std::process::Command;
+
+fn main() {
+    Command::new("forc").args(&["build"]).status().unwrap();
+}