Closes #ISSUE

Remove unused method `HttpClient::type_name`. Looking at the PR from a
year ago when it was added, it was never actually used for anything and
seems like a prototyping artifact.

Other misc changes for the `http_client` crate include:

- Use `derive_more::Deref` for `HttpClientWithUrl` (already used for
`HttpClientWithProxy`)
- Move `http_client::proxy()` higher up in the trait definition. (It was
in between methods that have default implementations)

Release Notes:

- N/A *or* Added/Fixed/Improved ...