feat: Move module run logic into its own script (#168)

This will help make the Containerfile just a little bit easier to read
(ignoring all the mounts lol). This would also allow us to add logic
later to support modules that run executables other than `*.sh`.

.github/workflows/build-pr.yml

@@ -53,7 +53,7 @@ jobs:
         id: build
         run: |
           if [ -n "${{ github.token }}" ]; then
-            earthly --ci --push +exports-script
+            earthly --ci --push +build-scripts
             echo "export=true" >> "$GITHUB_OUTPUT"
           fi
           earthly --ci +build