Explore support for custom IP address resolution

[nipafx]

JEP 418, shipped with JDK 18, allows customizing IP address resolution via an SPI. We should explore whether tests may benefit from temporarily redirecting host names to customizable IPs, e.g:

@Test
@Redirect(host = "example.org", to = "127.0.0.1")
void redirectedTest() {
	// ...
}

Hard-coding IP addresses into test code is probably not a good idea, so there's probably need for more maintainable options, maybe an external configuration file?

Explore!