Deprecate and remove `/api/v0` under the gateway port

[hacdias]

We've been wanting to deprecate the access to /api/v0 under the gateway path for at least two years, but I have not found any issue. This is the tracking issue.

• Kubo 0.27: deprecate /api/v0 from gateway port: core/corehttp: wrap gateway with headers, deprecate gateway /api/v0 #10311.
• Kubo 0.28: completely remove /api/v0 from gateway port: core/corehttp!: remove /api/v0 from gateway port #10352

[bahner]

Is this just for the gateway functionality or the API in general. Over localhost we'll still be using this or am I missing something? The issues here are a little confusing to understand.

[hacdias]

@bahner this is about removing /api/v0 on the gateway port (default 8080). The API will still be available on the API port (default 5001).