ClientContext without client_secret but with client_jwks

### oidcc version

3.*

### Erlang version

*

### Elixir version

*

### Summary

Figure out a solution to provide a client jwk without also providing a client secret.

### Current behavior

Currently the client context will not include the client JWK when passing `unauthenticated` for the secret.

### How to reproduce

```elixir
ClientContext.from_provider(Provider, "id", :unauthenticated, %{client_jwks: jwk})
```

### Expected behavior

Some way to only provide a client jwk and no secret.