Add support for direct DNS lookups behind a feature flag.

[YoEight]

Added: Add support for direct DNS lookups behind a feature flag.

Fixes #273

description

With this feature, the client will directly perform DNS lookups when probing for candidates during the connection process to a cluster of nodes. This mirrors the behavior from when the TCP API was still supported.

You can enable that feature using a connection string or a the connection builder.

connection string

esdb+discover://my.esdbcluster.com:1234?feature=dns-lookup

connection builder

     EventStoreDBClientSettings.builder()
        .dnsDiscover(true)
        .addHost("my.esdbcluster.com", 1234)
        .feature("dns-lookup")
        .buildConnectionSettings()