RFR: 8244202: Implementation of JEP 418: Internet-Address Resolution SPI

[Aleksei Efimov]

This change implements a new service provider interface for host name and address resolution, so that java.net.InetAddress API can make use of resolvers other than the platform's built-in resolver.

The following API classes are added to `java.net.spi` package to facilitate this:
- `InetAddressResolverProvider` -  abstract class defining a service, and is, essentially, a factory for `InetAddressResolver` resolvers.
- `InetAddressResolverProvider.Configuration ` - an interface describing the platform's built-in configuration for resolution operations that could be used to bootstrap a resolver construction, or to implement partial delegation of lookup operations.
- `InetAddressResolver` - an interface that defines methods for the fundamental forward and reverse lookup operations.
- `InetAddressResolver.LookupPolicy` - a class whose instances describe the characteristics of one forward lookup operation.  

More details in [JEP-418](https://openjdk.java.net/jeps/418).

Testing: new and existing `tier1:tier3` tests

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Commit messages:
 - 8244202: Implementation of JEP 418: Internet-Address Resolution SPI

Changes: https://git.openjdk.java.net/jdk/pull/5822/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5822&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8244202
  Stats: 2779 lines in 50 files changed: 2524 ins; 134 del; 121 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5822.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5822/head:pull/5822

PR: https://git.openjdk.java.net/jdk/pull/5822