Stream audit event for project group link create/destroy/update actions

What does this MR do and why?

Stream audit event for project group link create/destroy/update actions.

How to set up and validate locally

1. run rails console and execute below code to enter destination url

group = group.find 1 #replace with your group id here
destination_url = 'https://audit-event.requestcatcher.com/'
AuditEvents::ExternalAuditEventDestination.create(namespace_id: group.id, destination_url: destination_url)

1. Run gdk start.
2. create/destroy/update a project group link under group.
3. you can view audit event stream of approval action on https://audit-event.requestcatcher.com/

Example streaming json payloads

create project group link

{
  "id": 1,
  "author_id": 1,
  "entity_id": 24,
  "entity_type": "Project",
  "details": {
    "author_name": "example-user",
    "target_id": 31,
    "target_type": "Group",
    "target_details": "another-group",
    "custom_message": "Added project group link",
    "ip_address": "127.0.0.1",
    "entity_path": "example-group/example-project"
  },
  "ip_address": "127.0.0.1",
  "author_name": "example-user",
  "entity_path": "example-group/example-project",
  "target_details": "another-group",
  "created_at": "2022-07-04T00:43:09.318Z",
  "target_type": "Group",
  "target_id": 31,
  "event_type": "project_group_link_create"
}

update project group link

{
  "id": 1,
  "author_id": 1,
  "entity_id": 24,
  "entity_type": "Project",
  "details": {
    "author_name": "example-user",
    "target_id": 31,
    "target_type": "Group",
    "target_details": "another-group",
    "custom_message": "Changed project group link profile group_access from Developer to Guest",
    "ip_address": "127.0.0.1",
    "entity_path": "example-group/example-project"
  },
  "ip_address": "127.0.0.1",
  "author_name": "example-user",
  "entity_path": "example-group/example-project",
  "target_details": "another-group",
  "created_at": "2022-07-04T00:43:28.328Z",
  "target_type": "Group",
  "target_id": 31,
  "event_type": "project_group_link_update"
}

destroy project group link

{
  "id": 1,
  "author_id": 1,
  "entity_id": 24,
  "entity_type": "Project",
  "details": {
    "author_name": "example-user",
    "target_id": 31,
    "target_type": "Group",
    "target_details": "another-group",
    "custom_message": "Removed project group link",
    "ip_address": "127.0.0.1",
    "entity_path": "example-group/example-project"
  },
  "ip_address": "127.0.0.1",
  "author_name": "example-user",
  "entity_path": "example-group/example-project",
  "target_details": "another-group",
  "created_at": "2022-07-04T00:42:56.279Z",
  "target_type": "Group",
  "target_id": 31,
  "event_type": "project_group_link_destroy"
}

/cc @daveliu