feat: track resource replacements when claiming a prebuilt workspace (#17571)

Closes https://github.com/coder/internal/issues/369

We can't know whether a replacement (i.e. drift of terraform state
leading to a resource needing to be deleted/recreated) will take place
apriori; we can only detect it at `plan` time, because the provider
decides whether a resource must be replaced and it cannot be inferred
through static analysis of the template.

**This is likely to be the most common gotcha with using prebuilds,
since it requires a slight template modification to use prebuilds
effectively**, so let's head this off before it's an issue for
customers.

Drift details will now be logged in the workspace build logs:


![image](https://github.com/user-attachments/assets/da1988b6-2cbe-4a79-a3c5-ea29891f3d6f)

Plus a notification will be sent to template admins when this situation
arises:


![image](https://github.com/user-attachments/assets/39d555b1-a262-4a3e-b529-03b9f23bf66a)

A new metric - `coderd_prebuilt_workspaces_resource_replacements_total`
- will also increment each time a workspace encounters replacements.

We only track _that_ a resource replacement occurred, not how many. Just
one is enough to ruin a prebuild, but we can't know apriori which
replacement would cause this.
For example, say we have 2 replacements: a `docker_container` and a
`null_resource`; we don't know which one might
cause an issue (or indeed if either would), so we just track the
replacement.

---------

Signed-off-by: Danny Kopping <dannykopping@gmail.com>

docs/admin/templates/extending-templates/prebuilt-workspaces.md

@@ -163,6 +163,12 @@ resource "docker_container" "workspace" {
 
 Learn more about `ignore_changes` in the [Terraform documentation](https://developer.hashicorp.com/terraform/language/meta-arguments/lifecycle#ignore_changes).
 
+_A note on "immutable" attributes: Terraform providers may specify `ForceNew` on their resources' attributes. Any change
+to these attributes require the replacement (destruction and recreation) of the managed resource instance, rather than an in-place update.
+For example, the [`ami`](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/instance#ami-1) attribute on the `aws_instance` resource
+has [`ForceNew`](https://github.com/hashicorp/terraform-provider-aws/blob/main/internal/service/ec2/ec2_instance.go#L75-L81) set,
+since the AMI cannot be changed in-place._
+
 ### Current limitations
 
 The prebuilt workspaces feature has these current limitations: