Respect TTL of a DNS record for proxy config.

[minwoox]

The methods in ProxyConfig take an InetSocketAddress as an argument. e.g. ProxyConfig.connect(InetSocketAddress)
InetSocketAddress resolves the address only once when it's created so it doesn't respect TTL of a DNS record, thus the client will keep sending the request to the old proxy.
We can probably take an Endpoint instead of InetSocketAddress and reimplement it to respect the TTL in the client.

[chickenchickenlove]

@minwoox -nim,
I open a new PR.
When you have time, could you please take a look? 🙇‍♂️

My idea is very simple.
Whenever client try to send a request via proxy,
They get proxyConfig from ProxyConfigSelector.

Thus, If scheduler update InetSocketAddress instance periodically,
Client can get refreshed InetSocketAddress if it wants.

What do you think?