Build Fastly function during terraform plan

The Fastly function is now built whenever `terraform plan` is run. This
This ensures that the function is always up to date, and prevents users
from accidentally uploading a stale version of the WASM module.

This is implemented using an external data source [^1] inside Terraform.
The data source calls a script that compiles the function and returns
the path to the artifact.

[^1]: https://registry.terraform.io/providers/hashicorp/external/latest/docs/data-sources/data_source

Cargo.toml

@@ -2,5 +2,4 @@
 members = [
     "setup-deploy-keys",
     "ansible/roles/dev-desktop/files/team_login",
-    "terragrunt/modules/crates-io/compute-static"
 ]