Add router name to /info endpoint (huggingface#1854)

Add `router` key in `/info` endpoint and set it to
`env!("CARGO_PKG_NAME")` => so always set to `"text-generation-router"`
in TGI. Happy to change the naming if you think of a better one
(framework? package_name?)

The goal is to use this information in `InferenceClient` to know the
model is served with TGI. At the moment we can use
https://api-inference.huggingface.co/models/mistralai/Mistral-7B-Instruct-v0.2/info
to infer it is TGI-served because it returns information but having a
proper key would be better.


For context, a transformers-served model is only outputting `{"ok":
"ok"}` (see
[here](https://api-inference.huggingface.co/models/microsoft/DialoGPT-large/info)).

router/src/lib.rs

@@ -159,6 +159,8 @@ pub struct Info {
     #[schema(example = "32")]
     pub max_client_batch_size: usize,
     /// Router Info
+    #[schema(example = "text-generation-router")]
+    pub router: &'static str,
     #[schema(example = "0.5.0")]
     pub version: &'static str,
     #[schema(nullable = true, example = "null")]

router/src/server.rs

@@ -1564,6 +1564,7 @@ pub async fn run(
         max_batch_size,
         validation_workers,
         max_client_batch_size,
+        router: env!("CARGO_PKG_NAME"),
         version: env!("CARGO_PKG_VERSION"),
         sha: option_env!("VERGEN_GIT_SHA"),
         docker_label: option_env!("DOCKER_LABEL"),