Set connect_timeout and read_timeout on the storage client #7234

There is no exposed way to set a connect or read timeout on the storage client. The only per-attempt bound on HTTP requests is .with_attempt_timeout, which reqwest applies until the response body is fully received. That limits the total duration of a download, so it cannot detect a stalled read_object or write_object without also cutting off healthy large transfers.

Is your feature request related to a problem? Please describe.
We hit this in MaterializeInc/materialize#39983.

Describe the solution you'd like

• add fn with_connect_timeout(...) and fn with_read_timeout(...) on the storage::client::ClientBuilder.
• store the values in the gax::internal::ClientConfig.
• plumb the values into reqwest::ClientBuilder::connect_timeout and reqwest::ClientBuilder::read_timeout in gax-internal::http::ReqwestClient.
• and add tests.

These are client-level only, as reqwest applies them to pooled connections and does not support them per request.

Additional context
Related issues:
#2044 covers progress-based timeouts for uploads.
#4466 added attempt_timeout on the client.