RFR: 8254105: allow static members in inner classes, add binary compatibil…

[Vicente Romero]

Please review the fix for [JDK-8254105](https://bugs.openjdk.java.net/browse/JDK-8254105). The intention of the fix is
to allow static members to be declared inside inner classes. The spec allowing this change can be seen at [Local and
Nested Static
Declarations](http://cr.openjdk.java.net/~gbierman/8246771/8246771-20200928/specs/local-statics-jls.html). This change
is part of the [Records JEP](https://openjdk.java.net/jeps/395). The idea is to allow not only records to be defined
inside inner classes but also interfaces, enums, static classes and methods.

TIA,
Vicente

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

Commit messages:
 - 8254105: allow static members in inner classes, add binary compatibility tests

Changes: https://git.openjdk.java.net/jdk/pull/571/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=571&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254105
  Stats: 664 lines in 24 files changed: 459 ins; 140 del; 65 mod
  Patch: https://git.openjdk.java.net/jdk/pull/571.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/571/head:pull/571

PR: https://git.openjdk.java.net/jdk/pull/571