Refactor client configuration (#68)

* Refactor client configuration with new ClickHouseClientSettings class for more structured and DI-friendly config

* Add and update tests with new configuration approach

* Update examples

Author: alex-clickhouse

ClickHouse.Driver.Tests/ADO/ClickHouseClientSettingsTests.cs

@@ -12,7 +12,7 @@ public void ShouldHaveReasonableDefaults()
         {
             Assert.That(new ClickHouseConnectionStringBuilder().Port, Is.EqualTo(8123));
             Assert.That(new ClickHouseConnectionStringBuilder("Protocol=https").Port, Is.EqualTo(8443));
-            Assert.That(new ClickHouseConnectionStringBuilder().Database, Is.EqualTo("default"));
+            Assert.That(new ClickHouseConnectionStringBuilder().Database, Is.EqualTo(""));
             Assert.That(new ClickHouseConnectionStringBuilder().Username, Is.EqualTo("default"));
         });
     }