RFR: 8272215: Add InetAddress methods for parsing IP address literals

[Aleksei Efimov]

### Summary 

The changes in this PR add new API to `java.net.InetAddress`, `java.net.Inet4Address`, and
 `java.net.Inet6Address` classes to parse IP address literals:
 ```
method public static java.net.InetAddress java.net.InetAddress.ofLiteral(java.lang.String)
method public static java.net.Inet4Address java.net.Inet4Address.ofLiteral(java.lang.String)
method public static java.net.InetAddress java.net.Inet6Address.ofLiteral(java.lang.String)
``` 

### How new methods differ from existing ones

These methods differ from `InetAddress.getByName` and `InetAddress.getAllByName` in the following ways:
1. If a string supplied is not an address literal it is not forwarded to the system-wide resolver, but IllegalArgumentException is thrown instead. The system-wide resolver is never called from these new methods.
2. No reverse lookup is performed to resolve a hostname for the supplied address literal - the `InetAddress[46 ]` instances returned by the new `ofLiteral` API has no hostname set.
3. Each `ofLiteral` static method returns addresses of its class only. It gives the ability to check if an IP address literal is of a specific address type. 

### The list of noteworthy changes
- `IPv4-mapped IPv6 address` and `IPv4-compatible IPv6 addresses` require some special handling in the new API to implement all supported IP address types.  
- All address literal parsing code has been moved from `InetAddress.getAllByName` to address type-specific `Inet4Address.parseAddressString` and `Inet6Address.parseAddressString` methods.
- The text with scoped IPv6 addresses architecture draft IETF file has been replaced from `[draft-ietf-ipngwg-scoping-arch-04.txt]` to reference `RFC 4007: IPv6 Scoped Address Architecture`. The "RFC 4007" has been also added as `@ spec` into Inet6Address class-level Javadoc.

### Testing 

`jdk-tier1`, `jdk-tier2`, and `jdk-tier3` test sets show no failure with the changes.

`java/net` JCK tests are failing with new methods added failure (CSR is planned for this change):

Added Methods
-------------

java.net.Inet4Address:                  method public static java.net.Inet4Address java.net.Inet4Address.ofLiteral(java.lang.String)
java.net.Inet6Address:                  method public static java.net.InetAddress java.net.Inet6Address.ofLiteral(java.lang.String)
java.net.InetAddress:                   method public static java.net.InetAddress java.net.InetAddress.ofLiteral(java.lang.String)

-------------

Commit messages:
 - improve the ambiguous term readability according to Daniel comments
 - test update: run IPv6-scoped address with wrong scope-id test case only with at least 2 NI
 - Moving snippets to class-level docs per Michael suggestion, associated doc changes
 - Daniel suggestions
 - Merge branch 'master' into JDK-8272215_API_parse_IP_literals
 - update javadoc of internal utility methods.
 - updates for Inet6Address.ofLiteral return type, javadoc and the regression test
 - add null checks and NPE to methods javadoc
 - 8272215: Add InetAddress methods for parsing IP address literals

Changes: https://git.openjdk.org/jdk/pull/15775/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15775&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8272215
  Stats: 658 lines in 6 files changed: 579 ins; 57 del; 22 mod
  Patch: https://git.openjdk.org/jdk/pull/15775.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15775/head:pull/15775

PR: https://git.openjdk.org/jdk/pull/15775