Add resource for workspaces

[mathislucka]

Overview

First, consult REPO.md to view general guidelines on this task.

We want to add a resource for workspaces.

This is what we want to add:

list workspaces:

curl --request GET \
     --url https://api.cloud.deepset.ai/api/v1/workspaces \
     --header 'accept: application/json'

Response example:

[
    {
        "name": "copilot-testing",
        "workspace_id": "76d361b5-a551-40e3-a5c9-fdbc20028021",
        "languages": {},
        "default_idle_timeout_in_seconds": 43200
    },
    {
        "name": "default",
        "workspace_id": "91ee7798-004d-4808-906a-1777ea262d1c",
        "languages": {},
        "default_idle_timeout_in_seconds": 43200
    }
]

create workspace:

curl --request POST \
     --url https://api.cloud.deepset.ai/api/v1/workspaces \
     --header 'accept: application/json' \
     --header 'content-type: application/json' \
     --data '{"name":"some_name"}'

Returns empty 201 in case of success (use NoContentResponse that we already defined in src/deepset_mcp/api/shared_models.py).

get workspace:

curl --request GET \
     --url https://api.cloud.deepset.ai/api/v1/workspaces/some_workspace \
     --header 'accept: application/json'

{
  "default_idle_timeout_in_seconds": 0,
  "languages": {
    "additionalProp": {}
  },
  "name": "string",
  "workspace_id": "3fa85f64-5717-4562-b3fc-2c963f66afa6"
}

delete workspace:

curl --request DELETE \
     --url https://api.cloud.deepset.ai/api/v1/workspaces/some_workspace \
     --header 'accept: application/json'

returns 204 with no content on success

Implement the resource with these methods, create unit tests, create integration tests. Follow the instructions in REPO.md

Do NOT add any tools yet.

[mathislucka]

Work so far looks good. Go ahead and add the tests please.