Feat: implement sa tokens (#712)

* feat: implement sa access token resource

docs/resources/service_account_access_token.md

@@ -0,0 +1,84 @@
+---
+# generated by https://github.com/hashicorp/terraform-plugin-docs
+page_title: "stackit_service_account_access_token Resource - stackit"
+subcategory: ""
+description: |-
+  Service account access token schema.
+  ~> This resource is in beta and may be subject to breaking changes in the future. Use with caution. See our guide https://registry.terraform.io/providers/stackitcloud/stackit/latest/docs/guides/opting_into_beta_resources for how to opt-in to use beta resources.
+  Example Usage
+  Automatically rotate access tokens
+  
+  resource "stackit_service_account" "sa" {
+    project_id = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+    name       = "sa01"
+  }
+  
+  resource "time_rotating" "rotate" {
+    rotation_days = 80
+  }
+  
+  resource "stackit_service_account_access_token" "sa_token" {
+    project_id            = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+    service_account_email = stackit_service_account.sa.email
+    ttl_days              = 180
+  
+    rotate_when_changed = {
+      rotation = time_rotating.rotate.id
+    }
+  }
+---
+
+# stackit_service_account_access_token (Resource)
+
+Service account access token schema.
+
+~> This resource is in beta and may be subject to breaking changes in the future. Use with caution. See our [guide](https://registry.terraform.io/providers/stackitcloud/stackit/latest/docs/guides/opting_into_beta_resources) for how to opt-in to use beta resources.
+## Example Usage
+
+
+### Automatically rotate access tokens
+```terraform
+resource "stackit_service_account" "sa" {
+  project_id = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+  name       = "sa01"
+}
+
+resource "time_rotating" "rotate" {
+  rotation_days = 80
+}
+
+resource "stackit_service_account_access_token" "sa_token" {
+  project_id            = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+  service_account_email = stackit_service_account.sa.email
+  ttl_days              = 180
+
+  rotate_when_changed = {
+    rotation = time_rotating.rotate.id
+  }
+}
+
+```
+
+
+
+<!-- schema generated by tfplugindocs -->
+## Schema
+
+### Required
+
+- `project_id` (String) STACKIT project ID associated with the service account token.
+- `service_account_email` (String) Email address linked to the service account.
+
+### Optional
+
+- `rotate_when_changed` (Map of String) A map of arbitrary key/value pairs that will force recreation of the token when they change, enabling token rotation based on external conditions such as a rotating timestamp. Changing this forces a new resource to be created.
+- `ttl_days` (Number) Specifies the token's validity duration in days. If unspecified, defaults to 90 days.
+
+### Read-Only
+
+- `access_token_id` (String) Identifier for the access token linked to the service account.
+- `active` (Boolean) Indicate whether the token is currently active or inactive
+- `created_at` (String) Timestamp indicating when the access token was created.
+- `id` (String) Terraform's internal resource identifier. It is structured as "`project_id`,`service_account_email`,`access_token_id`".
+- `token` (String, Sensitive) JWT access token for API authentication. Prefixed by 'Bearer' and should be stored securely as it is irretrievable once lost.
+- `valid_until` (String) Estimated expiration timestamp of the access token. For precise validity, check the JWT details.