Add finalizer to link resource

[dhiaayachi]

Description

This adds a Finalizer to the Link controller. For now, this just handles deleting the hcp-config directory.

Testing & Reproduction steps

In addition to automated unit tests, I performed the following manual test.

1. Run consul like so:

   go run . agent -dev --log-level trace --data-dir /tmp/consul-test

2. Verify that hcp-config directory is created

   ➜  consul git:(nickcellino/CC-7338/add-link-finalizer) ls /tmp/consul-test
   checkpoint-signature hcp-config           node-id              serf
   ➜  consul git:(nickcellino/CC-7338/add-link-finalizer) ls /tmp/consul-test/hcp-config
   hcp-management-token server-config.json   successful-bootstrap
   ➜  consul git:(nickcellino/CC-7338/add-link-finalizer)

3. Create a Link:

   
   ➜  consul git:(nickcellino/CC-7338/add-link-finalizer) http PUT localhost:8500/api/hcp/v2/link/global data[resourceId]=$RESOURCE_ID data[clientSecret]=$CLIENT_SECRET data[clientId]=$CLIENT_ID X-Consul-Token:$CONSUL_HTTP_TOKEN
   HTTP/1.1 200 OK
   Content-Length: 617
   Content-Type: text/plain; charset=utf-8
   Date: Tue, 23 Jan 2024 21:27:06 GMT

{ "data": { "clientId": "...", "clientSecret": "...", "resourceId": "organization/d95434ef-1f14-4b17-b23e-1eb608bb9fda/project/e263159f-b9ea-468e-8dc5-ee3d23403fe2/hashicorp.consul.global-network-manager.cluster/my-cluster" }, "generation": "01HMW3GFRA65WXEG75PEQ4734K", "id": { "name": "global", "tenancy": { "peerName": "local" }, "type": { "group": "hcp", "groupVersion": "v2", "kind": "Link" }, "uid": "01HMW3GFRA65WXEG75PDFC5YQP" }, "version": "29" }

Verify from logs that finalizer has been added ✅ :

2024-01-23T16:27:06.763-0500 [TRACE] agent.server.controller-runtime: added finalizer: controller=consul.io/hcp/link managed_type=hcp.v2.Link resource-id="uid:\"01HMW3GFRA65WXEG75PDFC5YQP\" name:\"global\" type:{group:\"hcp\" group_version:\"v2\" kind:\"Link\"} tenancy:{peer_name:\"local\"}"

4. Delete the Link:
```shell-session
➜  consul git:(nickcellino/CC-7338/add-link-finalizer) http DELETE localhost:8500/api/hcp/v2/link/global
HTTP/1.1 204 No Content
Date: Tue, 23 Jan 2024 21:32:45 GMT

Verify from logs that cleanup has been called ✅ :

2024-01-23T16:32:45.578-0500 [TRACE] agent.server.controller-runtime: cleaning up link resource: controller=consul.io/hcp/link managed_type=hcp.v2.Link resource-id="uid:\"01HMW3GFRA65WXEG75PDFC5YQP\" name:\"global\" type:{group:\"hcp\" group_version:\"v2\" kind:\"Link\"} tenancy:{peer_name:\"local\"}"
2024-01-23T16:32:45.578-0500 [DEBUG] agent.server.controller-runtime: deleting hcp-config dir: controller=consul.io/hcp/link managed_type=hcp.v2.Link resource-id="uid:\"01HMW3GFRA65WXEG75PDFC5YQP\" name:\"global\" type:{group:\"hcp\" group_version:\"v2\" kind:\"Link\"} tenancy:{peer_name:\"local\"}" dir=/tmp/consul-test/hcp-config
2024-01-23T16:32:45.579-0500 [TRACE] agent.server.controller-runtime: removed finalizer: controller=consul.io/hcp/link managed_type=hcp.v2.Link resource-id="uid:\"01HMW3GFRA65WXEG75PDFC5YQP\" name:\"global\" type:{group:\"hcp\" group_version:\"v2\" kind:\"Link\"} tenancy:{peer_name:\"local\"}"
2024-01-23T16:32:45.579-0500 [TRACE] agent.server.controller-runtime: finally deleted: controller=consul.io/hcp/link managed_type=hcp.v2.Link resource-id="uid:\"01HMW3GFRA65WXEG75PDFC5YQP\" name:\"global\" type:{group:\"hcp\" group_version:\"v2\" kind:\"Link\"} tenancy:{peer_name:\"local\"}"

5. Verify that hcp-config directory no longer exists ✅

   ➜  consul git:(nickcellino/CC-7338/add-link-finalizer) ls /tmp/consul-test
   checkpoint-signature node-id              serf

6. Verify that Link no longer exists:

   
   ➜  consul git:(nickcellino/CC-7338/add-link-finalizer) http GET localhost:8500/api/hcp/v2/link/global
   HTTP/1.1 404 Not Found
   Content-Length: 52
   Content-Type: text/plain; charset=utf-8
   Date: Tue, 23 Jan 2024 21:34:14 GMT

rpc error: code = NotFound desc = resource not found

### Links
https://hashicorp.atlassian.net/browse/CC-7338

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### PR Checklist

* [x] updated test coverage
* [ ] external facing docs updated
* [ ] appropriate backport labels added
* [ ] not a security concern